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Amason ME, Li L, Harvest CK, Lacey CA, Miao EA. Validation of the Intermolecular Disulfide Bond in Caspase-2. BIOLOGY 2024; 13:49. [PMID: 38248479 PMCID: PMC10813798 DOI: 10.3390/biology13010049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 01/05/2024] [Accepted: 01/15/2024] [Indexed: 01/23/2024]
Abstract
Caspases are a family of proteins involved in cell death. Although several caspase members have been well characterized, caspase-2 remains enigmatic. Caspase-2 has been implicated in several phenotypes, but there has been no consensus in the field about its upstream activating signals or its downstream protein targets. In addition, the unique ability of caspase-2 to form a disulfide-bonded dimer has not been studied in depth. Herein, we investigate the disulfide bond in the context of inducible dimerization, showing that disulfide bond formation is dimerization dependent. We also explore and review several stimuli published in the caspase-2 field, test ferroptosis-inducing stimuli, and study in vivo infection models. We hypothesize that the disulfide bond will ultimately prove to be essential for the evolved function of caspase-2. Proving this will require the discovery of cell death phenotypes where caspase-2 is definitively essential.
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Affiliation(s)
- Megan E. Amason
- Department of Integrative Immunobiology, Duke University School of Medicine, Durham, NC 27710, USA
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, NC 27710, USA
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Department of Pathology, Duke University School of Medicine, Durham, NC 27710, USA
- Department of Cell Biology, Duke University School of Medicine, Durham, NC 27710, USA
| | - Lupeng Li
- Department of Integrative Immunobiology, Duke University School of Medicine, Durham, NC 27710, USA
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, NC 27710, USA
- Department of Pathology, Duke University School of Medicine, Durham, NC 27710, USA
- Department of Cell Biology, Duke University School of Medicine, Durham, NC 27710, USA
| | - Carissa K. Harvest
- Department of Integrative Immunobiology, Duke University School of Medicine, Durham, NC 27710, USA
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, NC 27710, USA
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Department of Pathology, Duke University School of Medicine, Durham, NC 27710, USA
- Department of Cell Biology, Duke University School of Medicine, Durham, NC 27710, USA
| | - Carolyn A. Lacey
- Department of Integrative Immunobiology, Duke University School of Medicine, Durham, NC 27710, USA
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, NC 27710, USA
- Department of Pathology, Duke University School of Medicine, Durham, NC 27710, USA
- Department of Cell Biology, Duke University School of Medicine, Durham, NC 27710, USA
| | - Edward A. Miao
- Department of Integrative Immunobiology, Duke University School of Medicine, Durham, NC 27710, USA
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, NC 27710, USA
- Department of Pathology, Duke University School of Medicine, Durham, NC 27710, USA
- Department of Cell Biology, Duke University School of Medicine, Durham, NC 27710, USA
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2
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The Nuclear Transporter Importin 13 Can Regulate Stress-Induced Cell Death through the Clusterin/KU70 Axis. Cells 2023; 12:cells12020279. [PMID: 36672214 PMCID: PMC9857240 DOI: 10.3390/cells12020279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Revised: 12/20/2022] [Accepted: 01/06/2023] [Indexed: 01/12/2023] Open
Abstract
The cellular response to environmental stresses, such as heat and oxidative stress, is dependent on extensive trafficking of stress-signalling molecules between the cytoplasm and nucleus, which potentiates stress-activated signalling pathways, eventually resulting in cell repair or death. Although Ran-dependent nucleocytoplasmic transport mediated by members of the importin (IPO) super family of nuclear transporters is believed to be responsible for nearly all macromolecular transit between nucleus and cytoplasm, it is paradoxically known to be significantly impaired under conditions of stress. Importin 13 (IPO13) is a unique bidirectional transporter that binds to and releases cargo in a Ran-dependent manner, but in some cases, cargo release from IPO13 is affected by loading of another cargo. To investigate IPO13's role in stress-activated pathways, we performed cell-based screens to identify a multitude of binding partners of IPO13 from human brain, lung, and testes. Analysis of the IPO13 interactome intriguingly indicated more than half of the candidate binding partners to be annotated for roles in stress responses; these included the pro-apoptotic protein nuclear clusterin (nCLU), as well as the nCLU-interacting DNA repair protein KU70. Here, we show, for the first time, that unlike other IPOs which are mislocalised and non-functional, IPO13 continues to translocate between the nucleus and cytoplasm under stress, retaining the capacity to import certain cargoes, such as nCLU, but not export others, such as KU70, as shown by analysis using fluorescence recovery after photobleaching. Importantly, depletion of IPO13 reduces stress-induced import of nCLU and protects against stress-induced cell death, with concomitant protection from DNA damage during stress. Overexpression/FACS experiments demonstrate that nCLU is dependent on IPO13 to trigger stress-induced cell death via apoptosis. Taken together, these results implicate IPO13 as a novel functional nuclear transporter in cellular stress, with a key role thereby in cell fate decision.
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3
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The p53-caspase-2 axis in the cell cycle and DNA damage response. Exp Mol Med 2021; 53:517-527. [PMID: 33854186 PMCID: PMC8102494 DOI: 10.1038/s12276-021-00590-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 02/15/2021] [Accepted: 02/16/2021] [Indexed: 02/08/2023] Open
Abstract
Caspase-2 was discovered almost three decades ago. It was one of the first two mammalian homologs of CED-3, the other being interleukin 1β-converting enzyme (ICE/caspase-1). Despite high similarity with CED-3 and its fly and mammalian counterparts (DRONC and caspase-9, respectively), the function of caspase-2 in apoptosis has remained enigmatic. A number of recent studies suggest that caspase-2 plays an important role in the regulation of p53 in response to cellular stress and DNA damage to prevent the proliferation and accumulation of damaged or aberrant cells. Here, we review these recent observations and their implications in caspase-2-mediated cellular death, senescence, and tumor suppression.
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4
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Al-Wassiti HA, Thomas DR, Wagstaff KM, Fabb SA, Jans DA, Johnston AP, Pouton CW. Adenovirus Terminal Protein Contains a Bipartite Nuclear Localisation Signal Essential for Its Import into the Nucleus. Int J Mol Sci 2021; 22:3310. [PMID: 33804953 PMCID: PMC8036708 DOI: 10.3390/ijms22073310] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 03/16/2021] [Accepted: 03/16/2021] [Indexed: 01/22/2023] Open
Abstract
Adenoviruses contain dsDNA covalently linked to a terminal protein (TP) at the 5'end. TP plays a pivotal role in replication and long-lasting infectivity. TP has been reported to contain a nuclear localisation signal (NLS) that facilitates its import into the nucleus. We studied the potential NLS motifs within TP using molecular and cellular biology techniques to identify the motifs needed for optimum nuclear import. We used confocal imaging microscopy to monitor the localisation and nuclear association of GFP fusion proteins. We identified two nuclear localisation signals, PV(R)6VP and MRRRR, that are essential for fully efficient TP nuclear entry in transfected cells. To study TP-host interactions further, we expressed TP in Escherichia coli (E. coli). Nuclear uptake of purified protein was determined in digitonin-permeabilised cells. The data confirmed that nuclear uptake of TP requires active transport using energy and shuttling factors. This mechanism of nuclear transport was confirmed when expressed TP was microinjected into living cells. Finally, we uncovered the nature of TP binding to host nuclear shuttling proteins, revealing selective binding to Imp β, and a complex of Imp α/β but not Imp α alone. TP translocation to the nucleus could be inhibited using selective inhibitors of importins. Our results show that the bipartite NLS is required for fully efficient TP entry into the nucleus and suggest that this translocation can be carried out by binding to Imp β or Imp α/β. This work forms the biochemical foundation for future work determining the involvement of TP in nuclear delivery of adenovirus DNA.
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Affiliation(s)
- Hareth A. Al-Wassiti
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne 3800, Australia;
| | - David R. Thomas
- Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Melbourne 3800, Australia; (D.R.T.); (K.M.W.); (D.A.J.)
| | - Kylie M. Wagstaff
- Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Melbourne 3800, Australia; (D.R.T.); (K.M.W.); (D.A.J.)
| | - Stewart A. Fabb
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne 3052, Australia;
| | - David A. Jans
- Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Melbourne 3800, Australia; (D.R.T.); (K.M.W.); (D.A.J.)
| | - Angus P. Johnston
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne 3800, Australia;
| | - Colin W. Pouton
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne 3800, Australia;
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5
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Kopeina GS, Zhivotovsky B. Caspase-2 as a master regulator of genomic stability. Trends Cell Biol 2021; 31:712-720. [PMID: 33752921 DOI: 10.1016/j.tcb.2021.03.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 02/16/2021] [Accepted: 03/01/2021] [Indexed: 02/06/2023]
Abstract
Genomic instability underlies genesis and the development of various types of cancer. During tumorigenesis, cancer initiating cells assume a set of features, which allow them to survive and proliferate. Different mutations and chromosomal alterations promote a selection of the most aggressive cancer clones that worsen the prognosis of the disease. Despite that caspase-2 was described as a protease fulfilling an initiator and an effector function in apoptosis, it has recently been discovered to play an important role in the maintenance of genomic integrity and normal chromosome configuration. This protein is able to stabilize p53 and affect the level of transcription factors, which activates cell response to oxidative stress. Here we focus on the discussion on the mechanism(s) of how caspase-2 regulates genomic stability and decreases tumorigenesis.
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Affiliation(s)
- Gelina S Kopeina
- Faculty of Medicine, MV Lomonosov Moscow State University, 119991 Moscow, Russia.
| | - Boris Zhivotovsky
- Faculty of Medicine, MV Lomonosov Moscow State University, 119991 Moscow, Russia; Division of Toxicology, Institute of Environmental Medicine, Karolinska Institutet, 17177 Stockholm, Sweden.
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6
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Brown-Suedel AN, Bouchier-Hayes L. Caspase-2 Substrates: To Apoptosis, Cell Cycle Control, and Beyond. Front Cell Dev Biol 2020; 8:610022. [PMID: 33425918 PMCID: PMC7785872 DOI: 10.3389/fcell.2020.610022] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Accepted: 12/03/2020] [Indexed: 01/12/2023] Open
Abstract
Caspase-2 belongs to the caspase family of proteins responsible for essential cellular functions including apoptosis and inflammation. Uniquely, caspase-2 has been identified as a tumor suppressor, but how it regulates this function is still unknown. For many years, caspase-2 has been considered an “orphan” caspase because, although it is able to induce apoptosis, there is an abundance of conflicting evidence that questions its necessity for apoptosis. Recent evidence supports that caspase-2 has non-apoptotic functions in the cell cycle and protection from genomic instability. It is unclear how caspase-2 regulates these opposing functions, which has made the mechanism of tumor suppression by caspase-2 difficult to determine. As a protease, caspase-2 likely exerts its functions by proteolytic cleavage of cellular substrates. This review highlights the known substrates of caspase-2 with a special focus on their functional relevance to caspase-2’s role as a tumor suppressor.
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Affiliation(s)
- Alexandra N Brown-Suedel
- Hematology-Oncology Section, Department of Pediatrics, Department of Molecular Cell Biology, Baylor College of Medicine, Houston, TX, United States.,William T. Shearer Center for Human Immunobiology, Texas Children's Hospital, Houston, TX, United States
| | - Lisa Bouchier-Hayes
- Hematology-Oncology Section, Department of Pediatrics, Department of Molecular Cell Biology, Baylor College of Medicine, Houston, TX, United States.,William T. Shearer Center for Human Immunobiology, Texas Children's Hospital, Houston, TX, United States
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7
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Fu S, Ding M, Wang J, Yin X, Zhou E, Kong L, Tu X, Guo Z, Wang A, Huang Y, Ye J. Identification and functional characterization of three caspases in Takifugu obscurus in response to bacterial infection. FISH & SHELLFISH IMMUNOLOGY 2020; 106:252-262. [PMID: 32735858 DOI: 10.1016/j.fsi.2020.07.047] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2019] [Revised: 07/14/2020] [Accepted: 07/21/2020] [Indexed: 06/11/2023]
Abstract
Caspases are evolutionarily conserved proteases, which are inextricably linked with the apoptosis and immune system in mammals. However, the expression pattern and function of some caspases remain largely unknown in pufferfish. In this study, three different pufferfish caspases (caspase-2 (Pfcasp-2), caspase-3 (Pfcasp-3), and caspase-8 (Pfcasp-8)) were characterized, and their expression patterns and functions were determined following Aeromonas hydrophila infection. The open reading frames of Pfcasp-2, -3, and -8 are 1,320, 846, and 1455 bp, respectively. Analyses of sequence alignment and phylogenetic tree showed that casp-2, -3, and -8 share 52%-65%, 33%-40%, 63%-78% overall sequence identities with those of other vertebrates, respectively. 3D structures of Pfcasp-2, -3, and -8 enjoy conservation in core area together, while each owns a distinctive profile. Comparisons of deduced amino acid sequences indicated that Pfcaspases possessed the caspase domain and conserved active sites like 'HG' and 'QACXG' (X for R or G). qRT-PCR results revealed that Pfcasp-2, -3, and -8 were expressed constitutively in a wide range of organs, especially in immune-related organs including whole blood and kidney. In vitro, the expressions of the three caspases (Pfcasp-2, 3, and -8) and immune-related genes (IgM and IL-8) were significantly up-regulated in kidney leukocytes after A. Hydrophila challenge and inhibitors treatment. The expressions of Pfcasp-2 and Pfcasp-3 were successfully inhibited in the kidney leukocytes by Ac-DEVD-CHO (an inhibitor to caspase-3), but the expression of Pfcasp-8 was not affected. Cellular localization analysis showed that the distribution of Pfcasp-2, -3, and -8 was in cytoplasm. Further, overexpression of Pfcasp-2, -3, or -8 was found to cause DNA damage and apoptosis, suggesting that three caspases may be related to apoptosis and mediate different apoptosis pathways in pufferfish. Moreover, the expressions of these caspases were also up-regulated in whole blood and kidney after A. hydrophila challenge, indicating their possible involvement in the immune response against A. hydrophia stimulation. Taken together, the results of this study suggest that the caspase-2,-3, and -8 may play an important role in the apoptosis and immune response in pufferfish.
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Affiliation(s)
- Shengli Fu
- School of Life Sciences, South China Normal University, Guangzhou, 510631, PR China; Guangdong South China Sea Key Laboratory of Aquaculture for Aquatic Economic Animals, Guangdong Ocean University, Zhanjiang, 524088, PR China
| | - Mingmei Ding
- School of medicine, Sun Yat-Sen University, Guangzhou, 510006, PR China
| | - Junru Wang
- School of Life Sciences, South China Normal University, Guangzhou, 510631, PR China
| | - Xiaoxue Yin
- School of Life Sciences, South China Normal University, Guangzhou, 510631, PR China
| | - Enxu Zhou
- School of Life Sciences, South China Normal University, Guangzhou, 510631, PR China
| | - Linghe Kong
- School of Life Sciences, South China Normal University, Guangzhou, 510631, PR China
| | - Xiao Tu
- School of Life Sciences, South China Normal University, Guangzhou, 510631, PR China
| | - Zheng Guo
- School of Life Sciences, South China Normal University, Guangzhou, 510631, PR China
| | - Anli Wang
- School of Life Sciences, South China Normal University, Guangzhou, 510631, PR China
| | - Yu Huang
- Guangdong South China Sea Key Laboratory of Aquaculture for Aquatic Economic Animals, Guangdong Ocean University, Zhanjiang, 524088, PR China
| | - Jianmin Ye
- School of Life Sciences, South China Normal University, Guangzhou, 510631, PR China.
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8
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Modulation of DNA Damage Response by Sphingolipid Signaling: An Interplay that Shapes Cell Fate. Int J Mol Sci 2020; 21:ijms21124481. [PMID: 32599736 PMCID: PMC7349968 DOI: 10.3390/ijms21124481] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 05/07/2020] [Accepted: 05/08/2020] [Indexed: 12/11/2022] Open
Abstract
Although once considered as structural components of eukaryotic biological membranes, research in the past few decades hints at a major role of bioactive sphingolipids in mediating an array of physiological processes including cell survival, proliferation, inflammation, senescence, and death. A large body of evidence points to a fundamental role for the sphingolipid metabolic pathway in modulating the DNA damage response (DDR). The interplay between these two elements of cell signaling determines cell fate when cells are exposed to metabolic stress or ionizing radiation among other genotoxic agents. In this review, we aim to dissect the mediators of the DDR and how these interact with the different sphingolipid metabolites to mount various cellular responses.
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9
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Vigneswara V, Ahmed Z. The Role of Caspase-2 in Regulating Cell Fate. Cells 2020; 9:cells9051259. [PMID: 32438737 PMCID: PMC7290664 DOI: 10.3390/cells9051259] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 05/11/2020] [Accepted: 05/12/2020] [Indexed: 12/13/2022] Open
Abstract
Caspase-2 is the most evolutionarily conserved member of the mammalian caspase family and has been implicated in both apoptotic and non-apoptotic signaling pathways, including tumor suppression, cell cycle regulation, and DNA repair. A myriad of signaling molecules is associated with the tight regulation of caspase-2 to mediate multiple cellular processes far beyond apoptotic cell death. This review provides a comprehensive overview of the literature pertaining to possible sophisticated molecular mechanisms underlying the multifaceted process of caspase-2 activation and to highlight its interplay between factors that promote or suppress apoptosis in a complicated regulatory network that determines the fate of a cell from its birth and throughout its life.
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10
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Sladky VC, Villunger A. Uncovering the PIDDosome and caspase-2 as regulators of organogenesis and cellular differentiation. Cell Death Differ 2020; 27:2037-2047. [PMID: 32415279 PMCID: PMC7308375 DOI: 10.1038/s41418-020-0556-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Revised: 04/24/2020] [Accepted: 04/28/2020] [Indexed: 02/08/2023] Open
Abstract
The PIDDosome is a multiprotein complex that drives activation of caspase-2, an endopeptidase originally implicated in apoptosis. Yet, unlike other caspases involved in cell death and inflammation, caspase-2 seems to exert additional versatile functions unrelated to cell death. These emerging roles range from control of transcription factor activity to ploidy surveillance. Thus, caspase-2 and the PIDDosome act as a critical regulatory unit controlling cellular differentiation processes during organogenesis and regeneration. These newly established functions of the PIDDosome and its downstream effector render its components attractive targets for drug-development aiming to prevent fatty liver diseases, neurodegenerative disorders or osteoporosis. ![]()
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Affiliation(s)
- Valentina C Sladky
- Division of Developmental Immunology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - Andreas Villunger
- Division of Developmental Immunology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria. .,Ludwig Boltzmann Institute for Rare and Undiagnosed Diseases, 1090, Vienna, Austria. .,CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, 1090, Vienna, Austria.
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Xu YR, Yang WX. Roles of three Es-Caspases during spermatogenesis and Cadmium-induced apoptosis in Eriocheir sinensis. Aging (Albany NY) 2019; 10:1146-1165. [PMID: 29851651 PMCID: PMC5990378 DOI: 10.18632/aging.101454] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Accepted: 05/18/2018] [Indexed: 01/08/2023]
Abstract
Functions of Caspases remain obscure in Crustacea. We studied the existence and participations of apoptosis-related factors in Eriocheir sinensis testis. Three Es-Caspases (Es-Caspase 3/ 7/ 8) in E. sinensis were cloned and characterized. We observed that three es-caspases mRNA had specific expression patterns during spermiogenesis, with weak signal around the nucleus and invaginated acrosomal vesicle in early-stage spermatids, became stronger in middle-stage, finally focused on the acrosomal tube and nucleus in mature sperm. We then investigated the immunostaining intensity and positional alterations of Es-Caspase 3, Es-Caspase 8 and p53 during spermatogenesis, which were correlated with the differential tendencies of cells to undergo apoptosis and specific organelles shaping processes. After apoptotic induction by Cadmium, Es-Caspase 8 increased gradually, while Es-Caspase 3 increased firstly and then decreased, Es-p53 initially decreased and then increased. These results implies that Es-Caspase 3/ Es-Caspase 8/ p53 may play roles in Cadmium-induced apoptosis during spermatogenesis, and Caspase 8-Caspase 3-p53 pathway may interact with extrinsic or intrinsic pathways to regulate the destiny of sperm cells. Our study revealed the indispensable roles of Caspases during spermatogenesis and the possible molecular interactions in response to the Cadmium-induced apoptosis in E. sinensis, which filled the gap of apoptotic mechanisms of crustacean.
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Affiliation(s)
- Ya-Ru Xu
- The Sperm Laboratory, College of Life Sciences, Zhejiang University, Hangzhou 310058, China
| | - Wan-Xi Yang
- The Sperm Laboratory, College of Life Sciences, Zhejiang University, Hangzhou 310058, China
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12
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Egorshina AY, Zamaraev AV, Lavrik IN, Zhivotovsky BD, Kopeina GS. Caspase-2 as an Oncosupressor and Metabolism Regulator: What Life Will Bring over the Long Run? Mol Biol 2018. [DOI: 10.1134/s0026893318050060] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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13
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Smidova A, Alblova M, Kalabova D, Psenakova K, Rosulek M, Herman P, Obsil T, Obsilova V. 14-3-3 protein masks the nuclear localization sequence of caspase-2. FEBS J 2018; 285:4196-4213. [PMID: 30281929 DOI: 10.1111/febs.14670] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Accepted: 09/28/2018] [Indexed: 12/13/2022]
Abstract
Caspase-2 is an apical protease responsible for the proteolysis of cellular substrates directly involved in mediating apoptotic signaling cascades. Caspase-2 activation is inhibited by phosphorylation followed by binding to the scaffolding protein 14-3-3, which recognizes two phosphoserines located in the linker between the caspase recruitment domain and the p19 domains of the caspase-2 zymogen. However, the structural details of this interaction and the exact role of 14-3-3 in the regulation of caspase-2 activation remain unclear. Moreover, the caspase-2 region with both 14-3-3-binding motifs also contains the nuclear localization sequence (NLS), thus suggesting that 14-3-3 binding may regulate the subcellular localization of caspase-2. Here, we report a structural analysis of the 14-3-3ζ:caspase-2 complex using a combined approach based on small angle X-ray scattering, NMR, chemical cross-linking, and fluorescence spectroscopy. The structural model proposed in this study suggests that phosphorylated caspase-2 and 14-3-3ζ form a compact and rigid complex in which the p19 and the p12 domains of caspase-2 are positioned within the central channel of the 14-3-3 dimer and stabilized through interactions with the C-terminal helices of both 14-3-3ζ protomers. In this conformation, the surface of the p12 domain, which is involved in caspase-2 activation by dimerization, is sterically occluded by the 14-3-3 dimer, thereby likely preventing caspase-2 activation. In addition, 14-3-3 protein binding to caspase-2 masks its NLS. Therefore, our results suggest that 14-3-3 protein binding to caspase-2 may play a key role in regulating caspase-2 activation. DATABASE: The atomic coordinates and structure factors have been deposited in the Protein Data Bank, www.ww pdb.org (PDB ID codes 6GKF and 6GKG).
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Affiliation(s)
- Aneta Smidova
- Department of Structural Biology of Signaling Proteins, Division BIOCEV, Institute of Physiology of the Czech Academy of Sciences, Vestec, Czech Republic
| | - Miroslava Alblova
- Department of Structural Biology of Signaling Proteins, Division BIOCEV, Institute of Physiology of the Czech Academy of Sciences, Vestec, Czech Republic
| | - Dana Kalabova
- Department of Structural Biology of Signaling Proteins, Division BIOCEV, Institute of Physiology of the Czech Academy of Sciences, Vestec, Czech Republic.,2nd Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Katarina Psenakova
- Department of Structural Biology of Signaling Proteins, Division BIOCEV, Institute of Physiology of the Czech Academy of Sciences, Vestec, Czech Republic.,Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Prague, Czech Republic
| | - Michal Rosulek
- Division BIOCEV, Institute of Microbiology of the Czech Academy of Sciences, Vestec, Czech Republic.,Department of Biochemistry, Faculty of Science, Charles University, Prague, Czech Republic
| | - Petr Herman
- Institute of Physics, Faculty of Mathematics and Physics, Charles University, Prague, Czech Republic
| | - Tomas Obsil
- Department of Structural Biology of Signaling Proteins, Division BIOCEV, Institute of Physiology of the Czech Academy of Sciences, Vestec, Czech Republic.,Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Prague, Czech Republic
| | - Veronika Obsilova
- Department of Structural Biology of Signaling Proteins, Division BIOCEV, Institute of Physiology of the Czech Academy of Sciences, Vestec, Czech Republic
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14
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Abstract
The cleavage of nuclear proteins by caspases promotes nuclear breakdown and, therefore, plays a key role in apoptosis execution. However, the detailed molecular mechanisms of these events remain unclear. To get more insights into the mechanisms of nuclear events during apoptosis we set up a rapid fractionation protocol for the separation of the cytoplasmic and nuclear fractions of cells undergoing cisplatin-induced apoptosis. Importantly, nuclear accumulation of effector caspase-3 as well as initiator caspase-2, -8 and -9 was observed using the developed protocol and immunofluorescence microscopy. The detection of caspases and their cleavage products in the nucleus occurred within the same time interval after cisplatin treatment and took place shortly before nuclear fragmentation. The entry of initiator caspases to the nucleus was independent of caspase-3. Given that all three initiator caspases had catalytic activity in the nuclei, our findings indicate that initiator caspases might participate in the proteolysis of nuclear components during apoptosis, promoting its disintegration and apoptotic cell death.
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15
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Robeson AC, Lindblom KR, Wojton J, Kornbluth S, Matsuura K. Dimer-specific immunoprecipitation of active caspase-2 identifies TRAF proteins as novel activators. EMBO J 2018; 37:e97072. [PMID: 29875129 PMCID: PMC6043850 DOI: 10.15252/embj.201797072] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Revised: 04/30/2018] [Accepted: 05/07/2018] [Indexed: 12/13/2022] Open
Abstract
Caspase-2 has been shown to initiate apoptotic cell death in response to specific intracellular stressors such as DNA damage. However, the molecular mechanisms immediately upstream of its activation are still poorly understood. We combined a caspase-2 bimolecular fluorescence complementation (BiFC) system with fluorophore-specific immunoprecipitation to isolate and study the active caspase-2 dimer and its interactome. Using this technique, we found that tumor necrosis factor receptor-associated factor 2 (TRAF2), as well as TRAF1 and 3, directly binds to the active caspase-2 dimer. TRAF2 in particular is necessary for caspase-2 activation in response to apoptotic cell death stimuli. Furthermore, we found that dimerized caspase-2 is ubiquitylated in a TRAF2-dependent manner at K15, K152, and K153, which in turn stabilizes the active caspase-2 dimer complex, promotes its association with an insoluble cellular fraction, and enhances its activity to fully commit the cell to apoptosis. Together, these data indicate that TRAF2 positively regulates caspase-2 activation and consequent cell death by driving its activation through dimer-stabilizing ubiquitylation.
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Affiliation(s)
- Alexander C Robeson
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC, USA
| | - Kelly R Lindblom
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC, USA
| | - Jeffrey Wojton
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC, USA
| | - Sally Kornbluth
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC, USA
| | - Kenkyo Matsuura
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC, USA
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16
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Kopeina GS, Prokhorova EA, Lavrik IN, Zhivotovsky B. Alterations in the nucleocytoplasmic transport in apoptosis: Caspases lead the way. Cell Prolif 2018; 51:e12467. [PMID: 29947118 DOI: 10.1111/cpr.12467] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Accepted: 04/19/2018] [Indexed: 12/13/2022] Open
Abstract
Apoptosis is a mode of regulated cell death that is indispensable for the morphogenesis, development and homeostasis of multicellular organisms. Caspases are cysteine-dependent aspartate-specific proteases, which function as initiators and executors of apoptosis. Caspases are cytosolic proteins that can cleave substrates located in different intracellular compartments during apoptosis. Many years ago, the involvement of caspases in the regulation of nuclear changes, a hallmark of apoptosis, was documented. Accumulated data suggest that apoptosis-associated alterations in nucleocytoplasmic transport are also linked to caspase activity. Here, we aim to discuss the current state of knowledge regarding this process. Particular attention will be focused on caspase nuclear entry and their functions in the demolition of the nucleus upon apoptotic stimuli.
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Affiliation(s)
- Gelina S Kopeina
- Faculty of Medicine, Lomonosov Moscow State University, Moscow, Russia
| | | | - Inna N Lavrik
- Faculty of Medicine, Lomonosov Moscow State University, Moscow, Russia.,Translational Inflammation Research, Medical Faculty, Otto von Guericke University, Magdeburg, Germany
| | - Boris Zhivotovsky
- Faculty of Medicine, Lomonosov Moscow State University, Moscow, Russia.,Division of Toxicology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
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17
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Forsberg J, Li X, Akpinar B, Salvatori R, Ott M, Zhivotovsky B, Olsson M. A caspase-2-RFXANK interaction and its implication for MHC class II expression. Cell Death Dis 2018; 9:80. [PMID: 29362422 PMCID: PMC5833739 DOI: 10.1038/s41419-017-0144-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Revised: 11/09/2017] [Accepted: 11/10/2017] [Indexed: 12/12/2022]
Abstract
Despite recent achievements implicating caspase-2 in tumor suppression, the enzyme stands out from the apoptotic caspase family as a factor whose function requires further clarification. To specify enzyme characteristics through the definition of interacting proteins in apoptotic or non-apoptotic settings, a yeast 2-hybrid (Y2H) screen was performed using the full-length protein as bait. The current report describes the analysis of a captured prey and putative novel caspase-2 interacting factor, the regulatory factor X-associated ankyrin-containing protein (RFXANK), previously associated with CIITA, the transactivator regulating cell-type specificity and inducibility of MHC class II gene expression. The interaction between caspase-2 and RFXANK was verified by co-immunoprecipitations using both exogenous and endogenous proteins, where the latter approach suggested that binding of the components occurs in the cytoplasm. Cellular co-localization was confirmed by transfection of fluorescently conjugated proteins. Enhanced caspase-2 processing in RFXANK-overexpressing HEK293T cells treated with chemotherapeutic agents further supported Y2H data. Yet, no distinct differences with respect to MHC class II expression were observed in plasma membranes of antigen-presenting cells derived from wild type and caspase-2-/- mice. In contrast, increased levels of the total MHC class II protein was evident in protein lysates from caspase-2 RNAi-silenced leukemia cell lines and B-cells isolated from gene-targeted mice. Together, these data identify a novel caspase-2-interacting factor, RFXANK, and indicate a potential non-apoptotic role for the enzyme in the control of MHC class II gene regulation.
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Affiliation(s)
- Jeremy Forsberg
- Division of Toxicology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Xinge Li
- Division of Toxicology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.,Science for Life Laboratory, Division of Translational Medicine and Chemical Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Birce Akpinar
- Division of Toxicology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Roger Salvatori
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Martin Ott
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Boris Zhivotovsky
- Division of Toxicology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden. .,Faculty of Medicine, Lomonosov Moscow State University, Moscow, Russia.
| | - Magnus Olsson
- Division of Toxicology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
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18
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Identification of novel antivirals inhibiting recognition of Venezuelan equine encephalitis virus capsid protein by the Importin α/β1 heterodimer through high-throughput screening. Antiviral Res 2018; 151:8-19. [PMID: 29337164 DOI: 10.1016/j.antiviral.2018.01.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2017] [Revised: 01/08/2018] [Accepted: 01/08/2018] [Indexed: 11/24/2022]
Abstract
Although the alphavirus Venezuelan equine encephalitis virus (VEEV) has been the cause of multiple outbreaks resulting in extensive human and equine mortality and morbidity, there are currently no anti-VEEV therapeutics available. VEEV pathogenicity is largely dependent on targeting of the viral capsid protein (CP) to the host cell nucleus through the nuclear transporting importin (Imp) α/β1 heterodimer. Here we perform a high-throughput screen, combined with nested counterscreens to identify small molecules able to inhibit the Impα/β1:CP interaction for the first time. Several compounds were able to significantly reduce viral replication in infected cells. Compound G281-1564 in particular could inhibit VEEV replication at low μM concentration, while showing minimal toxicity, with steady state and dynamic quantitative microscopic measurements confirming its ability to inhibit CP nuclear import. This study establishes the principle that inhibitors of CP nucleocytoplasmic trafficking can have potent antiviral activity against VEEV, and represents a platform for future development of safe anti-VEEV compounds with high efficacy and specificity.
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19
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Caspase-2 is required for skeletal muscle differentiation and myogenesis. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2018; 1865:95-104. [DOI: 10.1016/j.bbamcr.2017.07.016] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Revised: 07/20/2017] [Accepted: 07/28/2017] [Indexed: 02/07/2023]
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20
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Novel inhibitors targeting Venezuelan equine encephalitis virus capsid protein identified using In Silico Structure-Based-Drug-Design. Sci Rep 2017; 7:17705. [PMID: 29255256 PMCID: PMC5735092 DOI: 10.1038/s41598-017-17672-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Accepted: 11/29/2017] [Indexed: 11/09/2022] Open
Abstract
Therapeutics are currently unavailable for Venezuelan equine encephalitis virus (VEEV), which elicits flu-like symptoms and encephalitis in humans, with an estimated 14% of cases resulting in neurological disease. Here we identify anti-VEEV agents using in silico structure-based-drug-design (SBDD) for the first time, characterising inhibitors that block recognition of VEEV capsid protein (C) by the host importin (IMP) α/β1 nuclear transport proteins. From an initial screen of 1.5 million compounds, followed by in silico refinement and screening for biological activity in vitro, we identified 21 hit compounds which inhibited IMPα/β1:C binding with IC50s as low as 5 µM. Four compounds were found to inhibit nuclear import of C in transfected cells, with one able to reduce VEEV replication at µM concentration, concomitant with reduced C nuclear accumulation in infected cells. Further, this compound was inactive against a mutant VEEV that lacks high affinity IMPα/β1:C interaction, supporting the mode of its antiviral action to be through inhibiting C nuclear localization. This successful application of SBDD paves the way for lead optimization for VEEV antivirals, and is an exciting prospect to identify inhibitors for the many other viral pathogens of significance that require IMPα/β1 in their infectious cycle.
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21
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Brandi V, Di Lella V, Marino M, Ascenzi P, Polticelli F. A comprehensive in silico analysis of huntingtin and its interactome. J Biomol Struct Dyn 2017; 36:3155-3171. [PMID: 28920551 DOI: 10.1080/07391102.2017.1381646] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
A polyglutamine expansion of the N-terminal region of huntingtin (Htt) causes Huntington's disease, a severe neurodegenerative disorder. Htt huge multidomain structure, the presence of disordered regions, and the lack of sequence homologs of known structure, so far prevented structural studies of Htt, making the study of its structure-function relationships very difficult. In this work, the presence and location of five Htt ordered domains (named from Hunt1 to Hunt5) has been detected and the structure of these domains has been predicted for the first time using a combined threading/ab initio modeling approach. This work has led to the identification of a previously undetected HEAT repeats region in the Hunt3 domain. Furthermore, a putative function has been assigned to four out of the five domains. Hunt1 and Hunt5, displaying structural similarity with the regulatory subunit A of protein phosphatase 2A, are predicted to play a role in regulating the phosphorylation status of cellular proteins. Hunt2 and Hunt3 are predicted to be homologs of two yeast importins and to mediate vescicles transport and protein trafficking. Finally, a comprehensive analysis of the Htt interactome has been carried out and is discussed to provide a global picture of the Htt's structure-function relationships.
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Affiliation(s)
- Valentina Brandi
- a Department of Sciences , Roma Tre University, Viale Guglielmo Marconi 446 , Roma I-00146 , Italy
| | - Valentina Di Lella
- a Department of Sciences , Roma Tre University, Viale Guglielmo Marconi 446 , Roma I-00146 , Italy
| | - Maria Marino
- a Department of Sciences , Roma Tre University, Viale Guglielmo Marconi 446 , Roma I-00146 , Italy
| | - Paolo Ascenzi
- a Department of Sciences , Roma Tre University, Viale Guglielmo Marconi 446 , Roma I-00146 , Italy.,b Interdepartmental Laboratory for Electron Microscopy , Roma Tre University , Roma I-00146 , Italy
| | - Fabio Polticelli
- a Department of Sciences , Roma Tre University, Viale Guglielmo Marconi 446 , Roma I-00146 , Italy.,c National Institute of Nuclear Physics , Roma Tre University, Roma Tre Section , Roma I-00146 , Italy
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22
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Kalabova D, Smidova A, Petrvalska O, Alblova M, Kosek D, Man P, Obsil T, Obsilova V. Human procaspase-2 phosphorylation at both S139 and S164 is required for 14-3-3 binding. Biochem Biophys Res Commun 2017; 493:940-945. [PMID: 28943433 DOI: 10.1016/j.bbrc.2017.09.116] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Accepted: 09/20/2017] [Indexed: 11/29/2022]
Abstract
Procaspase-2 phosphorylation at several residues prevents its activation and blocks apoptosis. This process involves procaspase-2 phosphorylation at S164 and its binding to the scaffolding protein 14-3-3. However, bioinformatics analysis has suggested that a second phosphoserine-containing motif may also be required for 14-3-3 binding. In this study, we show that human procaspase-2 interaction with 14-3-3 is governed by phosphorylation at both S139 and S164. Using biochemical and biophysical approaches, we show that doubly phosphorylated procaspase-2 and 14-3-3 form an equimolar complex with a dissociation constant in the nanomolar range. Furthermore, our data indicate that other regions of procaspase-2, in addition to phosphorylation motifs, may be involved in the interaction with 14-3-3.
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Affiliation(s)
- Dana Kalabova
- Department of Structural Biology of Signaling Proteins, Division BIOCEV, Institute of Physiology of the Czech Academy of Sciences, Prumyslova 595, 252 50 Vestec, Czech Republic; 2nd Faculty of Medicine, Charles University, V Uvalu 84, 15006 Prague, Czech Republic
| | - Aneta Smidova
- Department of Structural Biology of Signaling Proteins, Division BIOCEV, Institute of Physiology of the Czech Academy of Sciences, Prumyslova 595, 252 50 Vestec, Czech Republic
| | - Olivia Petrvalska
- Department of Structural Biology of Signaling Proteins, Division BIOCEV, Institute of Physiology of the Czech Academy of Sciences, Prumyslova 595, 252 50 Vestec, Czech Republic; Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, 12843 Prague, Czech Republic
| | - Miroslava Alblova
- Department of Structural Biology of Signaling Proteins, Division BIOCEV, Institute of Physiology of the Czech Academy of Sciences, Prumyslova 595, 252 50 Vestec, Czech Republic
| | - Dalibor Kosek
- Department of Structural Biology of Signaling Proteins, Division BIOCEV, Institute of Physiology of the Czech Academy of Sciences, Prumyslova 595, 252 50 Vestec, Czech Republic; Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, 12843 Prague, Czech Republic
| | - Petr Man
- BIOCEV-Institute of Microbiology of the Czech Academy of Sciences, Prumyslova 595, 252 50 Vestec, Czech Republic
| | - Tomas Obsil
- Department of Structural Biology of Signaling Proteins, Division BIOCEV, Institute of Physiology of the Czech Academy of Sciences, Prumyslova 595, 252 50 Vestec, Czech Republic; Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, 12843 Prague, Czech Republic
| | - Veronika Obsilova
- Department of Structural Biology of Signaling Proteins, Division BIOCEV, Institute of Physiology of the Czech Academy of Sciences, Prumyslova 595, 252 50 Vestec, Czech Republic.
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23
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Ando K, Parsons MJ, Shah RB, Charendoff CI, Paris SL, Liu PH, Fassio SR, Rohrman BA, Thompson R, Oberst A, Sidi S, Bouchier-Hayes L. NPM1 directs PIDDosome-dependent caspase-2 activation in the nucleolus. J Cell Biol 2017; 216:1795-1810. [PMID: 28432080 PMCID: PMC5461015 DOI: 10.1083/jcb.201608095] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Revised: 01/19/2017] [Accepted: 03/03/2017] [Indexed: 12/11/2022] Open
Abstract
The PIDDosome (PIDD-RAIDD-caspase-2 complex) is considered to be the primary signaling platform for caspase-2 activation in response to genotoxic stress. Yet studies of PIDD-deficient mice show that caspase-2 activation can proceed in the absence of PIDD. Here we show that DNA damage induces the assembly of at least two distinct activation platforms for caspase-2: a cytoplasmic platform that is RAIDD dependent but PIDD independent, and a nucleolar platform that requires both PIDD and RAIDD. Furthermore, the nucleolar phosphoprotein nucleophosmin (NPM1) acts as a scaffold for PIDD and is essential for PIDDosome assembly in the nucleolus after DNA damage. Inhibition of NPM1 impairs caspase-2 processing, apoptosis, and caspase-2-dependent inhibition of cell growth, demonstrating that the NPM1-dependent nucleolar PIDDosome is a key initiator of the caspase-2 activation cascade. Thus we have identified the nucleolus as a novel site for caspase-2 activation and function.
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Affiliation(s)
- Kiyohiro Ando
- Department of Medicine, Division of Hematology/Oncology, Tisch Cancer Institute at Mount Sinai, New York, NY 10029.,Department of Developmental and Regenerative Biology and Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029
| | - Melissa J Parsons
- Department of Pediatrics, Division of Hematology-Oncology, Baylor College of Medicine, Houston, TX 77030
| | - Richa B Shah
- Department of Medicine, Division of Hematology/Oncology, Tisch Cancer Institute at Mount Sinai, New York, NY 10029.,Department of Developmental and Regenerative Biology and Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029
| | - Chloé I Charendoff
- Department of Pediatrics, Division of Hematology-Oncology, Baylor College of Medicine, Houston, TX 77030
| | - Sheré L Paris
- Department of Pediatrics, Division of Hematology-Oncology, Baylor College of Medicine, Houston, TX 77030
| | - Peter H Liu
- Department of Medicine, Division of Hematology/Oncology, Tisch Cancer Institute at Mount Sinai, New York, NY 10029.,Department of Developmental and Regenerative Biology and Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029
| | - Sara R Fassio
- Department of Pediatrics, Division of Hematology-Oncology, Baylor College of Medicine, Houston, TX 77030
| | - Brittany A Rohrman
- Department of Pediatrics, Division of Hematology-Oncology, Baylor College of Medicine, Houston, TX 77030
| | - Ruth Thompson
- Department of Medicine, Division of Hematology/Oncology, Tisch Cancer Institute at Mount Sinai, New York, NY 10029.,Department of Developmental and Regenerative Biology and Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029
| | - Andrew Oberst
- Department of Immunology, University of Washington, Seattle, WA 98109
| | - Samuel Sidi
- Department of Medicine, Division of Hematology/Oncology, Tisch Cancer Institute at Mount Sinai, New York, NY 10029 .,Department of Developmental and Regenerative Biology and Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029
| | - Lisa Bouchier-Hayes
- Department of Pediatrics, Division of Hematology-Oncology, Baylor College of Medicine, Houston, TX 77030 .,Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030
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24
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Abstract
Apoptosis is a cellular suicide program, which is on the one hand used to remove superfluous cells thereby promoting tissue or organ morphogenesis. On the other hand, the programmed killing of cells is also critical when potentially harmful cells emerge in a developing or adult organism thereby endangering survival. Due to its critical role apoptosis is tightly controlled, however so far, its regulation on the transcriptional level is less studied and understood. Hox genes, a highly conserved gene family encoding homeodomain transcription factors, have crucial roles in development. One of their prominent functions is to shape animal body plans by eliciting different developmental programs along the anterior-posterior axis. To this end, Hox proteins transcriptionally regulate numerous processes in a coordinated manner, including cell-type specification, differentiation, motility, proliferation as well as apoptosis. In this review, we will focus on how Hox proteins control organismal morphology and function by regulating the apoptotic machinery. We will first focus on well-established paradigms of Hox-apoptosis interactions and summarize how Hox transcription factors control morphological outputs and differentially shape tissues along the anterior-posterior axis by fine-tuning apoptosis in a healthy organism. We will then discuss the consequences when this interaction is disturbed and will conclude with some ideas and concepts emerging from these studies.
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25
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Aguilar A, Wagstaff KM, Suárez-Sánchez R, Zinker S, Jans DA, Cisneros B. Nuclear localization of the dystrophin-associated protein α-dystrobrevin through importin α2/β1 is critical for interaction with the nuclear lamina/maintenance of nuclear integrity. FASEB J 2015; 29:1842-58. [PMID: 25636738 DOI: 10.1096/fj.14-257147] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Accepted: 12/31/2014] [Indexed: 01/06/2023]
Abstract
Although α-dystrobrevin (DB) is assembled into the dystrophin-associated protein complex, which is central to cytoskeletal organization, it has also been found in the nucleus. Here we delineate the nuclear import pathway responsible for nuclear targeting of α-DB for the first time, together with the importance of nuclear α-DB in determining nuclear morphology. We map key residues of the nuclear localization signal of α-DB within the zinc finger domain (ZZ) using various truncated versions of the protein, and site-directed mutagenesis. Pulldown, immunoprecipitation, and AlphaScreen assays showed that the importin (IMP) α2/β1 heterodimer interacts with high affinity with the ZZ domain of α-DB. In vitro nuclear import assays using antibodies to specific importins, as well as in vivo studies using siRNA or a dominant negative importin construct, confirmed the key role of IMPα2/β1 in α-DB nuclear translocation. Knockdown of α-DB expression perturbed cell cycle progression in C2C12 myoblasts, with decreased accumulation of cells in S phase and, significantly, altered localization of lamins A/C, B1, and B2 with accompanying gross nuclear morphology defects. Because α-DB interacts specifically with lamin B1 in vivo and in vitro, nuclear α-DB would appear to play a key role in nuclear shape maintenance through association with the nuclear lamina.
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Affiliation(s)
- Areli Aguilar
- *Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, México City, Mexico; Nuclear Signalling Laboratory, Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia; and Laboratorio de Medicina Genómica, Departamento de Genética, Instituto Nacional de Rehabilitación, México City, Mexico
| | - Kylie M Wagstaff
- *Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, México City, Mexico; Nuclear Signalling Laboratory, Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia; and Laboratorio de Medicina Genómica, Departamento de Genética, Instituto Nacional de Rehabilitación, México City, Mexico
| | - Rocío Suárez-Sánchez
- *Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, México City, Mexico; Nuclear Signalling Laboratory, Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia; and Laboratorio de Medicina Genómica, Departamento de Genética, Instituto Nacional de Rehabilitación, México City, Mexico
| | - Samuel Zinker
- *Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, México City, Mexico; Nuclear Signalling Laboratory, Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia; and Laboratorio de Medicina Genómica, Departamento de Genética, Instituto Nacional de Rehabilitación, México City, Mexico
| | - David A Jans
- *Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, México City, Mexico; Nuclear Signalling Laboratory, Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia; and Laboratorio de Medicina Genómica, Departamento de Genética, Instituto Nacional de Rehabilitación, México City, Mexico
| | - Bulmaro Cisneros
- *Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, México City, Mexico; Nuclear Signalling Laboratory, Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia; and Laboratorio de Medicina Genómica, Departamento de Genética, Instituto Nacional de Rehabilitación, México City, Mexico
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26
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Overlapping binding sites for importin β1 and suppressor of fused (SuFu) on glioma-associated oncogene homologue 1 (Gli1) regulate its nuclear localization. Biochem J 2014; 461:469-76. [DOI: 10.1042/bj20130709] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The hedgehog signalling protein Gli1 has overlapping binding sites for the proteins importin β1 and SuFu at its N-terminus. These proteins compete to regulate the nuclear/cytoplasmic localization of Gli1, with importin β promoting nuclear import and SuFu preventing it.
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27
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Kaur G, Ly-Huynh JD, Jans DA. Intracellular calcium levels can regulate Importin-dependent nuclear import. Biochem Biophys Res Commun 2014; 450:812-7. [PMID: 24953690 DOI: 10.1016/j.bbrc.2014.06.047] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Accepted: 06/12/2014] [Indexed: 10/25/2022]
Abstract
We previously showed that increased intracellular calcium can modulate Importin (Imp)β1-dependent nuclear import of SRY-related chromatin remodeling proteins. Here we extend this work to show for the first time that high intracellular calcium inhibits Impα/β1- or Impβ1-dependent nuclear protein import generally. The basis of this relates to the mislocalisation of the transport factors Impβ1 and Ran, which show significantly higher nuclear localization in contrast to various other factors, and RCC1, which shows altered subnuclear localisation. The results here establish for the first time that intracellular calcium modulates conventional nuclear import through direct effects on the nuclear transport machinery.
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Affiliation(s)
- Gurpreet Kaur
- Nuclear Signalling Laboratory, Dept. of Biochemistry and Molecular Biology, Monash University, Australia
| | - Jennifer D Ly-Huynh
- Nuclear Signalling Laboratory, Dept. of Biochemistry and Molecular Biology, Monash University, Australia
| | - David A Jans
- Nuclear Signalling Laboratory, Dept. of Biochemistry and Molecular Biology, Monash University, Australia.
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28
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Suárez-Sánchez R, Aguilar A, Wagstaff KM, Velez G, Azuara-Medina PM, Gomez P, Vásquez-Limeta A, Hernández-Hernández O, Lieu KG, Jans DA, Cisneros B. Nucleocytoplasmic shuttling of the Duchenne muscular dystrophy gene product dystrophin Dp71d is dependent on the importin α/β and CRM1 nuclear transporters and microtubule motor dynein. BIOCHIMICA ET BIOPHYSICA ACTA 2014; 1843:985-1001. [PMID: 24486332 DOI: 10.1016/j.bbamcr.2014.01.027] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2013] [Revised: 12/17/2013] [Accepted: 01/24/2014] [Indexed: 01/08/2023]
Abstract
Even though the Duchenne muscular dystrophy (DMD) gene product Dystrophin Dp71d is involved in various key cellular processes through its role as a scaffold for structural and signalling proteins at the plasma membrane as well as the nuclear envelope, its subcellular trafficking is poorly understood. Here we map the nuclear import and export signals of Dp71d by truncation and point mutant analysis, showing for the first time that Dp71d shuttles between the nucleus and cytoplasm mediated by the conventional nuclear transporters, importin (IMP) α/β and the exportin CRM1. Binding was confirmed in cells using pull-downs, while in vitro binding assays showed direct, high affinity (apparent dissociation coefficient of c. 0.25nM) binding of Dp71d to IMPα/β. Interestingly, treatment of cells with the microtubule depolymerizing reagent nocodazole or the dynein inhibitor EHNA both decreased Dp71d nuclear localization, implying that Dp71d nuclear import may be facilitated by microtubules and the motor protein dynein. The role of Dp71d in the nucleus appears to relate in part to interaction with the nuclear envelope protein emerin, and maintenance of the integrity of the nuclear architecture. The clear implication is that Dp71d's previously unrecognised nuclear transport properties likely contribute to various, important physiological roles.
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Affiliation(s)
- R Suárez-Sánchez
- Departamento de Genética y Biología Molecular, Centro de Investigación y Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-IPN), México D.F, Mexico; Laboratorio de Medicina Genómica, Departamento de Genética, Instituto Nacional de Rehabilitación, México D.F, Mexico
| | - A Aguilar
- Departamento de Genética y Biología Molecular, Centro de Investigación y Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-IPN), México D.F, Mexico
| | - K M Wagstaff
- Nuclear Signalling Laboratory, Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC, Australia
| | - G Velez
- Departamento de Genética y Biología Molecular, Centro de Investigación y Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-IPN), México D.F, Mexico
| | - P M Azuara-Medina
- Departamento de Genética y Biología Molecular, Centro de Investigación y Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-IPN), México D.F, Mexico
| | - P Gomez
- Departamento de Genética y Biología Molecular, Centro de Investigación y Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-IPN), México D.F, Mexico
| | - A Vásquez-Limeta
- Departamento de Genética y Biología Molecular, Centro de Investigación y Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-IPN), México D.F, Mexico
| | - O Hernández-Hernández
- Laboratorio de Medicina Genómica, Departamento de Genética, Instituto Nacional de Rehabilitación, México D.F, Mexico
| | - K G Lieu
- Nuclear Signalling Laboratory, Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC, Australia
| | - D A Jans
- Nuclear Signalling Laboratory, Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC, Australia.
| | - B Cisneros
- Departamento de Genética y Biología Molecular, Centro de Investigación y Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-IPN), México D.F, Mexico.
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Vásquez-Limeta A, Wagstaff KM, Ortega A, Crouch DH, Jans DA, Cisneros B. Nuclear import of β-dystroglycan is facilitated by ezrin-mediated cytoskeleton reorganization. PLoS One 2014; 9:e90629. [PMID: 24599031 PMCID: PMC3944073 DOI: 10.1371/journal.pone.0090629] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Accepted: 02/04/2014] [Indexed: 12/12/2022] Open
Abstract
The β-dystroglycan (β-DG) protein has the ability to target to multiple sites in eukaryotic cells, being a member of diverse protein assemblies including the transmembranal dystrophin-associated complex, and a nuclear envelope-localised complex that contains emerin and lamins A/C and B1. We noted that the importin α2/β1-recognised nuclear localization signal (NLS) of β-DG is also a binding site for the cytoskeletal-interacting protein ezrin, and set out to determine whether ezrin binding might modulate β-DG nuclear translocation for the first time. Unexpectedly, we found that ezrin enhances rather than inhibits β-DG nuclear translocation in C2C12 myoblasts. Both overexpression of a phosphomimetic activated ezrin variant (Ez-T567D) and activation of endogenous ezrin through stimulation of the Rho pathway resulted in both formation of actin-rich surface protrusions and significantly increased nuclear translocation of β-DG as shown by quantitative microscopy and subcellular fractionation/Western analysis. In contrast, overexpression of a nonphosphorylatable inactive ezrin variant (Ez-T567A) or inhibition of Rho signaling, decreased nuclear translocation of β-DG concomitant with a lack of cell surface protrusions. Further, a role for the actin cytoskeleton in ezrin enhancement of β-DG nuclear translocation was implicated by the observation that an ezrin variant lacking its actin-binding domain failed to enhance nuclear translocation of β-DG, while disruption of the actin cytoskeleton led to a reduction in β-DG nuclear localization. Finally, we show that ezrin-mediated cytoskeletal reorganization enhances nuclear translocation of the cytoplasmic but not the transmembranal fraction of β-DG. This is the first study showing that cytoskeleton reorganization can modulate nuclear translocation of β-DG, with the implication that β-DG can respond to cytoskeleton-driven changes in cell morphology by translocating from the cytoplasm to the nucleus to orchestrate nuclear processes in response to the functional requirements of the cell.
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Affiliation(s)
- Alejandra Vásquez-Limeta
- Departamento de Genética y Biología Molecular, Centro de Investigación y Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-IPN), México D.F., Mexico
| | - Kylie M. Wagstaff
- Nuclear Signalling Laboratory, Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
| | - Arturo Ortega
- Departamento de Genética y Biología Molecular, Centro de Investigación y Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-IPN), México D.F., Mexico
| | - Dorothy H. Crouch
- School of Dentistry, University of Dundee, Dundee, Scotland, United Kingdom
| | - David A. Jans
- Nuclear Signalling Laboratory, Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
- * E-mail: (BC); david.jans@ monash.edu (DAJ)
| | - Bulmaro Cisneros
- Departamento de Genética y Biología Molecular, Centro de Investigación y Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-IPN), México D.F., Mexico
- * E-mail: (BC); david.jans@ monash.edu (DAJ)
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Abstract
Caspase-2 has been shown to function in apoptosis and in some non-apoptotic pathways, including tumor suppression and aging. Caspase-2 has some unique features and is the only caspase that constitutively localizes to the nucleus, although its nuclear function remains unknown. During apoptosis signaling, caspase-2 rapidly homodimerizes, which leads to its activation and proteolytic processing. The activation of caspase-2 can be measured by assessing its dimerization and/or cleavage of the caspase-2 zymogen and its substrates. This chapter outlines commonly used methods to purify recombinant caspase-2 and assess its activity and function in vitro and in cultured cells or tissue extracts.
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Affiliation(s)
- Loretta Dorstyn
- Centre for Cancer Biology, SA Pathology, Adelaide, Australia
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31
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Vakifahmetoglu-Norberg H, Norberg E, Perdomo AB, Olsson M, Ciccosanti F, Orrenius S, Fimia GM, Piacentini M, Zhivotovsky B. Caspase-2 promotes cytoskeleton protein degradation during apoptotic cell death. Cell Death Dis 2013; 4:e940. [PMID: 24309927 PMCID: PMC3877538 DOI: 10.1038/cddis.2013.463] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Revised: 10/23/2013] [Accepted: 10/24/2013] [Indexed: 01/28/2023]
Abstract
The caspase family of proteases cleaves large number of proteins resulting in major morphological and biochemical changes during apoptosis. Yet, only a few of these proteins have been reported to selectively cleaved by caspase-2. Numerous observations link caspase-2 to the disruption of the cytoskeleton, although it remains elusive whether any of the cytoskeleton proteins serve as bona fide substrates for caspase-2. Here, we undertook an unbiased proteomic approach to address this question. By differential proteome analysis using two-dimensional gel electrophoresis, we identified four cytoskeleton proteins that were degraded upon treatment with active recombinant caspase-2 in vitro. These proteins were degraded in a caspase-2-dependent manner during apoptosis induced by DNA damage, cytoskeleton disruption or endoplasmic reticulum stress. Hence, degradation of these cytoskeleton proteins was blunted by siRNA targeting of caspase-2 and when caspase-2 activity was pharmacologically inhibited. However, none of these proteins was cleaved directly by caspase-2. Instead, we provide evidence that in cells exposed to apoptotic stimuli, caspase-2 probed these proteins for proteasomal degradation. Taken together, our results depict a new role for caspase-2 in the regulation of the level of cytoskeleton proteins during apoptosis.
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Affiliation(s)
- H Vakifahmetoglu-Norberg
- Division of Toxicology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm 171 77, Sweden
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Vickers CJ, González-Páez GE, Wolan DW. Selective detection and inhibition of active caspase-3 in cells with optimized peptides. J Am Chem Soc 2013; 135:12869-76. [PMID: 23915420 DOI: 10.1021/ja406399r] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Caspases are a family of cysteine-aspartyl proteases that are well recognized for their essential roles in apoptosis and inflammation. Recently, caspases have also been linked to the promotion of other biologically important phenomena, such as cellular differentiation and proliferation. Dysregulation of the multifaceted and indispensable activities of caspases has been globally linked to several diseases, including cancer and neurodegenerative disorders; however, the specific caspase members responsible for these diseases have yet to be assigned. Activity-based probes (ABPs) and peptide-based inhibitors are instrumental in the detection and control of protease activity and serve as alternative methods to genetic approaches. Such molecules aid in the interrogation of specific proteases within cellular and animal models as well as help elucidate aberrant proteolytic function correlated to disease phenotypes. No ABPs or inhibitors have been discovered that specifically target one of the eleven human caspases in a cellular context. Therefore, ascribing distinct contributions to an individual caspase activity within naturally occurring biological systems is not possible. Herein, we describe a peptide series optimized for the selective detection and inhibition of active caspase-3 in cells. These compounds exhibit low nanomolar potency against caspase-3 with >120-fold selectivity over caspase-7 which shares 77% active site identity. Our ability to individually target wild-type active caspase-3 for detection and cell permeable inhibition is a valuable proof-of-concept methodology that can be readily employed to probe the significance of caspase-3 in apoptosis, neurological disorders, cardiovascular diseases, and sepsis.
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Affiliation(s)
- Chris J Vickers
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA
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Puccini J, Dorstyn L, Kumar S. Caspase-2 as a tumour suppressor. Cell Death Differ 2013; 20:1133-9. [PMID: 23811850 DOI: 10.1038/cdd.2013.87] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2013] [Revised: 06/06/2013] [Accepted: 06/07/2013] [Indexed: 01/02/2023] Open
Abstract
Ever since its discovery 20 years ago, caspase-2 has been enigmatic and its function somewhat controversial. Although many in vitro studies suggested that caspase-2 was important for apoptosis, demonstrating an in vivo cell death role for this caspase has been more problematic, with caspase-2-deficient mice showing limited, tissue-specific cell death defects. Recent results from different laboratories suggest that at least one of its physiological roles in animals is to protect against cellular stress and transformation. As such, loss of caspase-2 augments tumorigenesis in some mouse models of cancer, assigning a tumour suppressor function to this enigmatic caspase. This review focuses on this seemingly non-apoptotic function of caspase-2 as a tumour suppressor and reconciles some of the recent findings in the field.
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Affiliation(s)
- J Puccini
- Department of Haematology, Centre for Cancer Biology, SA Pathology, Frome Road, Adelaide, SA 5000, Australia
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34
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Tinnikov AA, Samuels HH. A novel cell lysis approach reveals that caspase-2 rapidly translocates from the nucleus to the cytoplasm in response to apoptotic stimuli. PLoS One 2013; 8:e61085. [PMID: 23596516 PMCID: PMC3626589 DOI: 10.1371/journal.pone.0061085] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Accepted: 03/07/2013] [Indexed: 11/22/2022] Open
Abstract
Unlike other caspases, caspase-2 appears to be a nuclear protein although immunocytochemical studies have suggested that it may also be localized to the cytosol and golgi. Where and how caspase-2 is activated in response to apoptotic signals is not clear. Earlier immunocytochemistry studies suggest that caspase-2 is activated in the nucleus and through cleavage of BID leads to increased mitochondrial permeability. More recent studies using bimolecular fluorescence complementation found that caspase-2 oligomerization that leads to activation only occurs in the cytoplasm. Thus, apoptotic signals may lead to activation of caspase-2 which may already reside in the cytoplasm or lead to release of nuclear caspase-2 to the extra-nuclear cytoplasmic compartment. It has not been possible to study release of nuclear caspase-2 to the cytoplasm by cell fractionation studies since cell lysis is known to release nuclear caspase-2 to the extra-nuclear fraction. This is similar to what is known about unliganded nuclear estrogen receptor-α (ERα ) when cells are disrupted. In this study we found that pre-treatment of cells with N-ethylmaleimide (NEM), which alkylates cysteine thiol groups in proteins, completely prevents redistribution of caspase-2 and ERα from the nucleus to the extra-nuclear fraction when cells are lysed. Using this approach we provide evidence that apoptotic signals rapidly leads to a shift of caspase-2 from the nucleus to the extra-nuclear fraction, which precedes the detection of apoptosis. These findings are consistent with a model where apoptotic signals lead to a rapid shift of caspase-2 from the nucleus to the cytoplasm where activation occurs.
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Affiliation(s)
- Alexander A. Tinnikov
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, New York, United States of America
| | - Herbert H. Samuels
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, New York, United States of America
- * E-mail:
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Affiliation(s)
- Luca L. Fava
- Division of Developmental Immunology, BIOCENTER, Medical University Innsbruck, Innsbruck, Austria
| | - Florian J. Bock
- Division of Developmental Immunology, BIOCENTER, Medical University Innsbruck, Innsbruck, Austria
| | - Stephan Geley
- Division of Molecular Pathophysiology, BIOCENTER, Medical University Innsbruck, Innsbruck, Austria
| | - Andreas Villunger
- Division of Developmental Immunology, BIOCENTER, Medical University Innsbruck, Innsbruck, Austria
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36
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Kaur G, Lieu KG, Jans DA. 70-kDa heat shock cognate protein hsc70 mediates calmodulin-dependent nuclear import of the sex-determining factor SRY. J Biol Chem 2012; 288:4148-57. [PMID: 23235156 DOI: 10.1074/jbc.m112.436741] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We recently showed that the developmentally important family of SOX (SRY (sex determining region on the Y chromosome)-related high mobility group (HMG) box) proteins require the calcium-binding protein calmodulin (CaM) for optimal nuclear accumulation, with clinical mutations in SRY that specifically impair nuclear accumulation via this pathway resulting in XY sex reversal. However, the mechanism by which CaM facilitates nuclear accumulation is unknown. Here, we show, for the first time, that the 70-kDa heat shock cognate protein hsc70 plays a key role in CaM-dependent nuclear import of SRY. Using a reconstituted nuclear import assay, we show that antibodies to hsc70 significantly reduce nuclear accumulation of wild type SRY and mutant derivatives thereof that retain CaM-dependent nuclear import, with an increased rate of nuclear accumulation upon addition of both CaM and hsc70, in contrast to an SRY mutant derivative with impaired CaM binding. siRNA knockdown of hsc70 in intact cells showed similar results, indicating clear dependence upon hsc70 for CaM-dependent nuclear import. Analysis using the technique of fluorescence recovery after photobleaching indicated that hsc70 is required for the maximal rate of SRY nuclear import in living cells but has no impact upon SRY nuclear retention/nuclear dynamics. Finally, we demonstrate direct binding of hsc70 to the SRY·CaM complex, with immunoprecipitation experiments from cell extracts showing association of hsc70 with wild type SRY, but not with a mutant derivative with impaired CaM binding, dependent on Ca(2+). Our novel findings strongly implicate hsc70 in CaM-dependent nuclear import of SRY.
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Affiliation(s)
- Gurpreet Kaur
- Nuclear Signalling Laboratory, Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia
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37
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Oksayan S, Wiltzer L, Rowe CL, Blondel D, Jans DA, Moseley GW. A novel nuclear trafficking module regulates the nucleocytoplasmic localization of the rabies virus interferon antagonist, P protein. J Biol Chem 2012; 287:28112-21. [PMID: 22700958 PMCID: PMC3431689 DOI: 10.1074/jbc.m112.374694] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2012] [Revised: 06/13/2012] [Indexed: 12/25/2022] Open
Abstract
Regulated nucleocytoplasmic transport of proteins is central to cellular function and dysfunction during processes such as viral infection. Active protein trafficking into and out of the nucleus is dependent on the presence within cargo proteins of intrinsic specific modular signals for nuclear import (nuclear localization signals, NLSs) and export (nuclear export signals, NESs). Rabies virus (RabV) phospho (P) protein, which is largely responsible for antagonising the host anti-viral response, is expressed as five isoforms (P1-P5). The subcellular trafficking of these isoforms is thought to depend on a balance between the activities of a dominant N-terminal NES (N-NES) and a distinct C-terminal NLS (C-NLS). Specifically, the N-NES-containing isoforms P1 and P2 are cytoplasmic, whereas the shorter P3-P5 isoforms, which lack the N-NES, are believed to be nuclear through the activity of the C-NLS. Here, we show for the first time that RabV P contains an additional strong NLS in the N-terminal region (N-NLS), which, intriguingly, overlaps with the N-NES. This arrangement represents a novel nuclear trafficking module where the N-NLS is inactive in P1 but becomes activated in P3, concomitant with truncation of the N-NES, to become the principal targeting signal conferring nuclear accumulation. Understanding this unique switch arrangement of overlapping, co-regulated NES/NLS sequences is vital to delineating the critical role of RabV P protein in viral infection.
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Affiliation(s)
- Sibil Oksayan
- From the Viral Immune Evasion and Pathogenicity Laboratory and
- Nuclear Signaling Laboratory, Department of Biochemistry and Molecular Biology, Monash University, 3800 Victoria, Australia and
| | - Linda Wiltzer
- From the Viral Immune Evasion and Pathogenicity Laboratory and
- Nuclear Signaling Laboratory, Department of Biochemistry and Molecular Biology, Monash University, 3800 Victoria, Australia and
| | - Caitlin L. Rowe
- From the Viral Immune Evasion and Pathogenicity Laboratory and
- Nuclear Signaling Laboratory, Department of Biochemistry and Molecular Biology, Monash University, 3800 Victoria, Australia and
| | - Danielle Blondel
- the Laboratoire de Virologie Moléculaire et Structurale, Centre de Recherche de Gif, CNRS 91198 Gif-sur-Yvette, France
| | - David A. Jans
- Nuclear Signaling Laboratory, Department of Biochemistry and Molecular Biology, Monash University, 3800 Victoria, Australia and
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Dorstyn L, Puccini J, Wilson CH, Shalini S, Nicola M, Moore S, Kumar S. Caspase-2 deficiency promotes aberrant DNA-damage response and genetic instability. Cell Death Differ 2012; 19:1288-98. [PMID: 22498700 DOI: 10.1038/cdd.2012.36] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Caspase-2 is an initiator caspase, which has been implicated to function in apoptotic and non-apoptotic signalling pathways, including cell-cycle regulation, DNA-damage signalling and tumour suppression. We previously demonstrated that caspase-2 deficiency enhances E1A/Ras oncogene-induced cell transformation and augments lymphomagenesis in the EμMyc mouse model. Caspase-2(-/-) mouse embryonic fibroblasts (casp2(-/-) MEFs) show aberrant cell-cycle checkpoint regulation and a defective apoptotic response following DNA damage. Disruption of cell-cycle checkpoints often leads to genomic instability (GIN), which is a common phenotype of cancer cells and can contribute to cellular transformation. Here we show that caspase-2 deficiency results in increased DNA damage and GIN in proliferating cells. Casp2(-/-) MEFs readily escape senescence in culture and exhibit increased micronuclei formation and sustained DNA damage during cell culture and following γ-irradiation. Metaphase analyses demonstrated that a lack of caspase-2 is associated with increased aneuploidy in both MEFs and in EμMyc lymphoma cells. In addition, casp2(-/-) MEFs and lymphoma cells exhibit significantly decreased telomere length. We also noted that loss of caspase-2 leads to defective p53-mediated signalling and decreased trans-activation of p53 target genes upon DNA damage. Our findings suggest that loss of caspase-2 serves as a key function in maintaining genomic integrity, during cell proliferation and following DNA damage.
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Affiliation(s)
- L Dorstyn
- Department of Haematology, Centre for Cancer Biology/SA Pathology, Adelaide, SA, Australia.
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Janssens S, Tinel A. The PIDDosome, DNA-damage-induced apoptosis and beyond. Cell Death Differ 2011; 19:13-20. [PMID: 22095286 DOI: 10.1038/cdd.2011.162] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
P53-induced protein with a death domain (PIDD) was cloned as a death domain (DD)-containing protein whose expression is induced by p53. It was later described as the core of a molecular platform-activating caspase-2, named the PIDDosome. These first results pointed towards a role for PIDD in apoptosis, in response to DNA damage. Identification of new PIDDosome complexes involved in DNA repair and nuclear factor-κB signaling challenged this early concept. PIDD functions are growing as new complexes and new interaction partners are being discovered, and as additional functions are being revealed. A fascinating feature of PIDD lies within its complex and tight regulation mechanisms, which allow the molecule to fine-tune its different functions: from transcriptional regulation to the expression of different isoforms, and from the interaction with regulatory proteins to an ingenious post-translational cleavage mechanism generating various active fragments with specific functions. Further studies still need to be carried out to provide answers to many unresolved issues and to reconcile conflicting results. This review aims at providing an overview of the current PIDD knowledge status.
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Affiliation(s)
- S Janssens
- GROUP-ID Consortium, Department of Pulmonary Medicine, University Hospital of Ghent, Ghent, Belgium.
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40
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Lamkanfi M, Kanneganti TD. Regulation of immune pathways by the NOD-like receptor NLRC5. Immunobiology 2011; 217:13-6. [PMID: 22024701 DOI: 10.1016/j.imbio.2011.08.011] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2011] [Accepted: 08/31/2011] [Indexed: 11/18/2022]
Abstract
Members of the nucleotide-binding and oligomerization domain (NOD)-like receptor (NLR) family are quickly emerging as critical regulators of innate and adaptive immune responses during microbial infection and autoimmunity. The NLR family member NLRC5 was recently proposed to function as a positive and negative regulator of antiviral immune responses. NLRC5 has also been implicated in regulation of inflammasome signaling and MHC class I transcription. Some of these functions have recently been assessed in NLRC5-deficient mice and immune cells. Here, we summarize and review the newly gained knowledge on the structure, expression profile and putative functions of NLRC5 in regulating immune responses and host defense.
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41
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Hunt RC, Geetha S, Allen CE, Hershko K, Fathke R, Kong PL, Plum E, Struble EB, Soejima K, Friedman S, Garfield S, Balaji S, Kimchi-Sarfaty C. Detection of a secreted metalloprotease within the nuclei of liver cells. MOLECULAR BIOSYSTEMS 2011; 7:2012-8. [PMID: 21479334 PMCID: PMC3128511 DOI: 10.1039/c0mb00303d] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
ADAMTS13 is a secreted zinc metalloprotease expressed by various cell types. Here, we investigate its cellular pathway in endogenously expressing liver cell lines and after transient transfection with ADAMTS13. Besides compartmentalizations of the cellular secretory system, we detected an appreciable level of endogenous ADAMTS13 within the nucleus. A positively charged amino acid cluster (R-Q-R-Q-R-Q-R-R) present in the ADAMTS13 propeptide may act as a nuclear localization signal (NLS). Fusing this NLS-containing region to eGFP greatly potentiated its nuclear localization. Bioinformatics analysis suggests that the ADAMTS13 CUB-2 domain has a double-stranded beta helix (DSBH) structural architecture characteristic of various protein-protein interaction modules like nucleoplasmins, class I collagenase, tumor necrosis factor ligand superfamily, supernatant protein factor (SPF) and the B1 domain of neuropilin-2. Based on this contextual evidence and that largely conserved polar residues could be mapped on to a template CUB domain homolog, we hypothesize that a region in the ADAMTS13 CUB-2 domain with conserved polar residues might be involved in protein-protein interaction within the nucleus.
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Affiliation(s)
- Ryan C. Hunt
- Laboratory of Hemostasis, Division of Hematology, Center for Biologic, Food and Drug Administration, Bethesda, Maryland 20892
| | - S Geetha
- Laboratory of Hemostasis, Division of Hematology, Center for Biologic, Food and Drug Administration, Bethesda, Maryland 20892
| | - Courtni E. Allen
- Laboratory of Hemostasis, Division of Hematology, Center for Biologic, Food and Drug Administration, Bethesda, Maryland 20892
| | - Klilah Hershko
- Laboratory of Hemostasis, Division of Hematology, Center for Biologic, Food and Drug Administration, Bethesda, Maryland 20892
| | - Robert Fathke
- Laboratory of Hemostasis, Division of Hematology, Center for Biologic, Food and Drug Administration, Bethesda, Maryland 20892
| | - Philip L. Kong
- Laboratory of Hemostasis, Division of Hematology, Center for Biologic, Food and Drug Administration, Bethesda, Maryland 20892
| | - Elizabeth Plum
- Laboratory of Hemostasis, Division of Hematology, Center for Biologic, Food and Drug Administration, Bethesda, Maryland 20892
| | - Evi Budo Struble
- Laboratory of Plasma Derivatives, Division of Hematology, Center for Biologic, Food and Drug Administration, Bethesda, Maryland 20892
| | - Kenji Soejima
- First Research Department, The Chemo-Sero-Therapeutic Research Institute, Kumamoto, Japan
| | - Scott Friedman
- Division of Liver Diseases, Mount Sinai School of Medicine, New York, NY 10029
| | - Susan Garfield
- Laboratory of Experimental Carcinogenesis, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892
| | - S Balaji
- National Center for Biotechnology Information, National Library of Medicine, National Institute of Health, Bethesda, Maryland, 20892
| | - Chava Kimchi-Sarfaty
- Laboratory of Hemostasis, Division of Hematology, Center for Biologic, Food and Drug Administration, Bethesda, Maryland 20892
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Wagstaff KM, Rawlinson SM, Hearps AC, Jans DA. An AlphaScreen®-based assay for high-throughput screening for specific inhibitors of nuclear import. ACTA ACUST UNITED AC 2011; 16:192-200. [PMID: 21297106 DOI: 10.1177/1087057110390360] [Citation(s) in RCA: 127] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Specific viral proteins enter the nucleus of infected cells to perform essential functions, as part of the viral life cycle. The integrase (IN) molecule of human immunodeficiency virus (HIV)-1 is of particular interest in this context due to its integral role in integrating the HIV genome into that of the infected host cell. Most IN-based antiviral compounds target the IN/DNA interaction, but since IN must first enter the nucleus before it can perform these critical functions, nuclear transport of IN is also an attractive target for therapeutic intervention. Here the authors describe a novel high-throughput screening assay for identifying inhibitors of nuclear import, particularly IN, based on amplified luminescent proximity homogeneous assay (AlphaScreen(®)) technology, which is high throughput, requires low amounts of material, and is efficient and cost-effective. The authors use the assay to screen for specific inhibitors of the interaction between IN and its nuclear transport receptor importin α/β, successfully identifying several inhibitors of the IN/importin α/β interaction. Importantly, they demonstrate that one of the identified compounds, mifepristone, is effective in preventing active nuclear transport of IN in transfected cells and hence may represent a useful anti-HIV therapeutic. The screen also identified broad-spectrum importin α/β inhibitors such as ivermectin, which may represent useful tools for nuclear transport research in the future. The authors validate the activity and specificity of mifepristone and ivermectin in inhibiting nuclear protein import in living cells, underlining the utility of the screening approach.
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Affiliation(s)
- Kylie M Wagstaff
- Nuclear Signalling Laboratory, Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
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Roth DM, Moseley GW, Pouton CW, Jans DA. Mechanism of microtubule-facilitated "fast track" nuclear import. J Biol Chem 2011; 286:14335-51. [PMID: 21339293 DOI: 10.1074/jbc.m110.210302] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Although the microtubule (MT) cytoskeleton has been shown to facilitate nuclear import of specific cancer-regulatory proteins including p53, retinoblastoma protein, and parathyroid hormone-related protein (PTHrP), the MT association sequences (MTASs) responsible and the nature of the interplay between MT-dependent and conventional importin (IMP)-dependent nuclear translocation are unknown. Here we used site-directed mutagenesis, live cell imaging, and direct IMP and MT binding assays to map the MTAS of PTHrP for the first time, finding that it is within a short modular region (residues 82-108) that overlaps with the IMPβ1-recognized nuclear localization signal (residues 66-108) of PTHrP. Importantly, fluorescence recovery after photobleaching experiments indicated that disruption of the MT network or mutation of the MTAS of PTHrP decreases the rate of nuclear import by 2-fold. Moreover, MTAS functions depend on mutual exclusivity of binding of PTHrP to MTs and IMPβ1 such that, following MT-dependent trafficking toward the nucleus, perinuclear PTHrP can be displaced from MTs by IMPβ1 prior to import into the nucleus. This is the first molecular definition of an MTAS that facilitates protein nuclear import as well as the first delineation of the mechanism whereby cargo is transferred directly from the cytoskeleton to the cellular nuclear import apparatus. The results have broad significance with respect to fundamental processes regulating cell physiology/transformation.
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Affiliation(s)
- Daniela Martino Roth
- Nuclear Signalling Laboratory, Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia
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Shukla A, Tapadia MG. Differential localization and processing of apoptotic proteins in Malpighian tubules of Drosophila during metamorphosis. Eur J Cell Biol 2011; 90:72-80. [DOI: 10.1016/j.ejcb.2010.08.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2010] [Revised: 08/13/2010] [Accepted: 08/26/2010] [Indexed: 01/11/2023] Open
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Kaur G, Jans DA. Dual nuclear import mechanisms of sex determining factor SRY: intracellular Ca2+ as a switch. FASEB J 2010; 25:665-75. [PMID: 21051653 DOI: 10.1096/fj.10-173351] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The sex-determining region on the Y chromosome (SRY) has 2 nuclear localization signals (NLSs) that flank the DNA binding high mobility group (HMG) domain; the β-NLS and the CaM-NLS, which mediate nuclear transport through importin β1 (Impβ1) and the calcium-binding protein calmodulin (CaM), respectively. Here we reconstitute the nuclear import mediated by the 2 NLSs for the first time in vitro, establishing Ran independence of CaM-NLS-dependent transport. The β- and CaM-NLSs were found to be independently functional out of the context of the SRY HMG domain, dependent on Impβ1 and CaM binding, respectively. Intriguingly, direct protein binding assays also indicated competitive binding of Impβ1 and CaM to the SRY HMG domain. To assess the potential role of intracellular calcium in modulating SRY nuclear accumulation, Cos-7 cells expressing SRY and control constructs were treated with agents elevating or reducing intracellular Ca(2+) levels. The in vivo results, supported by experiments in vitro where transport was assessed with or without 2 μM Ca(2+), indicate a Ca(2+)-dependent mode of nuclear transport via the CaM-NLS/CaM, with inhibition of β-NLS/Impβ1-mediated nuclear import by intracellular Ca(2+). The results imply mutual exclusivity of nuclear transport via the 2 NLSs with intracellular Ca(2+) as the switch between the 2.
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Affiliation(s)
- Gurpreet Kaur
- Nuclear Signalling Laboratory, Department of Biochemistry and Molecular Biology, Monash University Bldg. 77, Monash Vic. 3800, Australia
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Wang XJ, Cao Q, Liu X, Wang KT, Mi W, Zhang Y, Li LF, LeBlanc AC, Su XD. Crystal structures of human caspase 6 reveal a new mechanism for intramolecular cleavage self-activation. EMBO Rep 2010; 11:841-7. [PMID: 20890311 DOI: 10.1038/embor.2010.141] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2010] [Revised: 08/12/2010] [Accepted: 08/17/2010] [Indexed: 11/09/2022] Open
Abstract
Dimeric effectors caspase 3 and caspase 7 are activated by initiator caspase processing. In this study, we report the crystal structures of effector caspase 6 (CASP6) zymogen and N-Acetyl-Val-Glu-Ile-Asp-al-inhibited CASP6. Both of these forms of CASP6 have a dimeric structure, and in CASP6 zymogen the intersubunit cleavage site (190)TEVD(193) is well structured and inserts into the active site. This positions residue Asp 193 to be easily attacked by the catalytic residue Cys 163. We demonstrate biochemically that intramolecular cleavage at Asp 193 is a prerequisite for CASP6 self-activation and that this activation mechanism is dependent on the length of the L2 loop. Our results indicate that CASP6 can be activated and regulated through intramolecular self-cleavage.
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Affiliation(s)
- Xiao-Jun Wang
- National Laboratory of Protein Engineering & Plant Genetic Engineering, Peking University, Haidian District, Beijing, People's Republic of China
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Calmodulin-dependent nuclear import of HMG-box family nuclear factors: importance of the role of SRY in sex reversal. Biochem J 2010; 430:39-48. [PMID: 20528776 PMCID: PMC2911679 DOI: 10.1042/bj20091758] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The HMG (high-mobility group)-box-containing chromatin-remodelling factor SRY (sex-determining region on the Y chromosome) plays a key role in sex determination. Its role in the nucleus is critically dependent on two NLSs (nuclear localization signals) that flank its HMG domain: the C-terminally located 'beta-NLS' that mediates nuclear transport through Impbeta1 (importin beta1) and the N-terminally located 'CaM-NLS' which is known to recognize the calcium-binding protein CaM (calmodulin). In the present study, we examined a number of missense mutations in the SRY CaM-NLS from human XY sex-reversed females for the first time, showing that they result in significantly reduced nuclear localization of GFP (green fluorescent protein)-SRY fusion proteins in transfected cells compared with wild-type. The CaM antagonist CDZ (calmidazolium chloride) was found to significantly reduce wild-type SRY nuclear accumulation, indicating dependence of SRY nuclear import on CaM. Intriguingly, the CaM-NLS mutants were all resistant to CDZ's effects, implying a loss of interaction with CaM, which was confirmed by direct binding experiments. CaM-binding/resultant nuclear accumulation was the only property of SRY found to be impaired by two of the CaM-NLS mutations, implying that inhibition of CaM-dependent nuclear import is the basis of sex reversal in these cases. Importantly, the CaM-NLS is conserved in other HMG-box-domain-containing proteins such as SOX-2, -9, -10 and HMGN1, all of which were found for the first time to rely on CaM for optimal nuclear localization. CaM-dependent nuclear translocation is thus a common mechanism for this family of important transcription factors.
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Fulcher AJ, Dias MM, Jans DA. Binding of p110 retinoblastoma protein inhibits nuclear import of simian virus SV40 large tumor antigen. J Biol Chem 2010; 285:17744-53. [PMID: 20356831 PMCID: PMC2878538 DOI: 10.1074/jbc.m109.055491] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2009] [Revised: 03/29/2010] [Indexed: 01/19/2023] Open
Abstract
Nuclear import of the simian virus 40 large tumor antigen (T-ag) is dependent on its nuclear localization signal (NLS) within amino acids 126-132 that is recognized by the importin alpha/beta1 heterodimer, as well as a protein kinase CK2 site at serine 112 upstream of the NLS, which enhances the interaction approximately 50-fold. Here we show for the first time that T-ag nuclear import is negatively regulated by N-terminal sequences (amino acids 102-110), which represent the binding site (BS) for the retinoblastoma (Rb) tumor suppressor protein (p110(Rb)). Quantitative confocal laser scanning microscopic analysis of the transport properties of T-ag constructs with or without Rb binding site mutations in living transfected cells or in a reconstituted nuclear transport system indicates that the presence of the RbBS significantly reduces nuclear accumulation of T-ag. A number of approaches, including the analysis of T-ag nuclear import in an isogenic cell pair with and without functional p110(Rb) implicate p110(Rb) binding as being responsible for the reduced nuclear accumulation, with the Ser(106) phosphorylation site within the RbBS appearing to enhance the inhibitory effect. Immunoprecipitation experiments confirmed association of T-ag and p110(Rb) and dependence thereof on negative charge at Ser(106). The involvement of p110(Rb) in modulating T-ag nuclear transport has implications for the regulation of nuclear import of other proteins from viruses of medical significance that interact with p110(Rb), and how this may relate to transformation.
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Affiliation(s)
- Alex James Fulcher
- From the Nuclear Signaling Laboratory, Department of Biochemistry and Molecular Biology, Monash University, Victoria, Clayton 3800, Australia and
| | - Manisha M. Dias
- From the Nuclear Signaling Laboratory, Department of Biochemistry and Molecular Biology, Monash University, Victoria, Clayton 3800, Australia and
| | - David A. Jans
- From the Nuclear Signaling Laboratory, Department of Biochemistry and Molecular Biology, Monash University, Victoria, Clayton 3800, Australia and
- the ARC Centre of Excellence for Biotechnology and Development, Victoria, Melbourne 3000, Australia
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Lara-Chacón B, de León MB, Leocadio D, Gómez P, Fuentes-Mera L, Martínez-Vieyra I, Ortega A, Jans DA, Cisneros B. Characterization of an Importin α/β-recognized nuclear localization signal in β-dystroglycan. J Cell Biochem 2010; 110:706-17. [DOI: 10.1002/jcb.22581] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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Abstract
Caspase-2 is the most evolutionarily conserved of all the caspases, yet it has a poorly defined role in apoptotic pathways. This is mainly due to a dearth of techniques to determine the activation status of caspase-2 and the lack of an abnormal phenotype in caspase-2 deficient mice. Nevertheless, emerging evidence suggests that caspase-2 may have important functions in a number of stress-induced cell death pathways, in cell cycle maintenance and regulation of tumour progression. This review discusses recent advances that have been made to help elucidate the true role of this elusive caspase and the potential contribution of caspase-2 to the pathology of human diseases including cancer.
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Affiliation(s)
- Lisa Bouchier-Hayes
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
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