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Kędzierska H, Piekiełko-Witkowska A. Splicing factors of SR and hnRNP families as regulators of apoptosis in cancer. Cancer Lett 2017; 396:53-65. [PMID: 28315432 DOI: 10.1016/j.canlet.2017.03.013] [Citation(s) in RCA: 149] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Revised: 03/08/2017] [Accepted: 03/08/2017] [Indexed: 12/19/2022]
Abstract
SR and hnRNP proteins were initially discovered as regulators of alternative splicing: the process of controlled removal of introns and selective joining of exons through which multiple transcripts and, subsequently, proteins can be expressed from a single gene. Alternative splicing affects genes involved in all crucial cellular processes, including apoptosis. During cancerogenesis impaired apoptotic control facilitates survival of cells bearing molecular aberrations, contributing to their unrestricted proliferation and chemoresistance. Apparently, SR and hnRNP proteins regulate all levels of expression of apoptotic genes, including transcription initiation and elongation, alternative splicing, mRNA stability, translation, and protein degradation. The frequently disturbed expressions of SR/hnRNP proteins in cancers lead to impaired functioning of target apoptotic genes, including regulators of the extrinsic (Fas, caspase-8, caspase-2, c-FLIP) and the intrinsic pathway (Apaf-1, caspase-9, ICAD), genes encoding Bcl-2 proteins, IAPs, and p53 tumor suppressor. Prototypical members of SR/hnRNP families, SRSF1 and hnRNP A1, promote synthesis of anti-apoptotic splice variants of Bcl-x and Mcl-1, which results in attenuation of programmed cell death in breast cancer and chronic myeloid leukemia. SR/hnRNP proteins significantly affect responses to chemotherapy, acting as mediators or modulators of drug-induced apoptosis. Aberrant expression of SRSF1 and hnRNP K can interfere with tumor responses to chemotherapy in pancreatic and liver cancers. Currently, a number of splicing factor inhibitors is being tested in pre-clinical and clinical trials. In this review we discuss recent findings on the role of SR and hnRNP proteins in apoptotic control in cancer cells as well as their significance in anticancer treatments.
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Affiliation(s)
- Hanna Kędzierska
- Department of Biochemistry and Molecular Biology, Centre of Postgraduate Medical Education, ul. Marymoncka 99/103, 01-813 Warsaw, Poland
| | - Agnieszka Piekiełko-Witkowska
- Department of Biochemistry and Molecular Biology, Centre of Postgraduate Medical Education, ul. Marymoncka 99/103, 01-813 Warsaw, Poland.
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Engineered cellular gene-replacement platform for selective and inducible proteolytic profiling. Proc Natl Acad Sci U S A 2015; 112:8344-9. [PMID: 26106156 DOI: 10.1073/pnas.1504141112] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cellular demolition during apoptosis is completed by executioner caspases, that selectively cleave more than 1,500 proteins but whose individual roles are challenging to assess. Here, we used an optimized site-specific and inducible protease to examine the role of a classic apoptotic node, the caspase-activated DNase (CAD). CAD is activated when caspases cleave its endogenous inhibitor ICAD, resulting in the characteristic DNA laddering of apoptosis. We describe a posttranscriptional gene replacement (PTGR) approach where endogenous biallelic ICAD is knocked down and simultaneously replaced with an engineered allele that is susceptible to inducible cleavage by tobacco etch virus protease. Remarkably, selective activation of CAD alone does not induce cell death, although hallmarks of DNA damage are detected in human cancer cell lines. Our data strongly support that the highly cooperative action of CAD and inhibition of DNA repair systems are critical for the DNA laddering phenotype in apoptosis. Furthermore, the PTGR approach provides a general means for replacing wild-type protein function with a precisely engineered mutant at the transcriptional level that should be useful for cell engineering studies.
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Samejima K, Ogawa H, Ageichik AV, Peterson KL, Kaufmann SH, Kanemaki MT, Earnshaw WC. Auxin-induced rapid degradation of inhibitor of caspase-activated DNase (ICAD) induces apoptotic DNA fragmentation, caspase activation, and cell death: a cell suicide module. J Biol Chem 2014; 289:31617-23. [PMID: 25248749 PMCID: PMC4223357 DOI: 10.1074/jbc.m114.583542] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Caspase-activated DNase (CAD) is a major apoptotic nuclease, responsible for DNA fragmentation and chromatin condensation during apoptosis. CAD is normally activated in apoptosis as a result of caspase cleavage of its inhibitory chaperone ICAD. Other aspects of CAD regulation are poorly understood. In particular, it has been unclear whether direct CAD activation in non-apoptotic living cells can trigger cell death. Taking advantage of the auxin-inducible degron (AID) system, we have developed a suicide system with which ICAD is rapidly degraded in living cells in response to the plant hormone auxin. Our studies demonstrate that rapid ICAD depletion is sufficient to activate CAD and induce cell death in DT40 and yeast cells. In the vertebrate cells, ectopic CAD activation triggered caspase activation and subsequent hallmarks of caspase-dependent apoptotic changes, including phosphatidylserine exposure and nuclear fragmentation. These observations not only suggest that CAD activation drives apoptosis through a positive feedback loop, but also identify a unique suicide system that can be used for controlling gene-modified organisms.
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Affiliation(s)
- Kumiko Samejima
- From the Wellcome Trust Centre for Cell Biology, University of Edinburgh, King's Buildings, Max Born Crescent, Edinburgh EH9 3BF, Scotland, United Kingdom,
| | - Hiromi Ogawa
- From the Wellcome Trust Centre for Cell Biology, University of Edinburgh, King's Buildings, Max Born Crescent, Edinburgh EH9 3BF, Scotland, United Kingdom
| | - Alexander V Ageichik
- From the Wellcome Trust Centre for Cell Biology, University of Edinburgh, King's Buildings, Max Born Crescent, Edinburgh EH9 3BF, Scotland, United Kingdom
| | | | | | - Masato T Kanemaki
- the Centre for Frontier Research, National Institute of Genetics, ROIS, and Department of Genetics, SOKENDAI, Yata 1111, Mishima, Shizuoka 411-8540, Japan, and the Japan Science and Technology Agency (JST), PREST, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - William C Earnshaw
- From the Wellcome Trust Centre for Cell Biology, University of Edinburgh, King's Buildings, Max Born Crescent, Edinburgh EH9 3BF, Scotland, United Kingdom,
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Deoxyribonuclease inhibitors. Eur J Med Chem 2014; 88:101-11. [PMID: 25042005 DOI: 10.1016/j.ejmech.2014.07.040] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 07/10/2014] [Accepted: 07/11/2014] [Indexed: 02/06/2023]
Abstract
Deoxyribonucleases (DNases) are a class of enzymes able to catalyze DNA hydrolysis. DNases play important roles in cell function, while DNase inhibitors control or modify their activities. This review focuses on DNase inhibitors. Some DNase inhibitors have been isolated from various natural sources, such as humans, animals (beef, calf, rabbit and rat), plants (Nicotiana tabacum), and microorganisms (some Streptomyces and Adenovirus species, Micromonospora echinospora and Escherichia coli), while others have been obtained by chemical synthesis. They differ in chemical structure (various proteins, nucleotides, anthracycline and aminoglycoside antibiotics, synthetic organic and inorganic compounds) and mechanism of action (forming complexes with DNases or DNA). Some of the inhibitors are specific toward only one type of DNase, while others are active towards two or more. Physico-chemical properties of DNase inhibitors are calculated using the Molinspiration tool and most of them meet all criteria for good solubility and permeability. DNase inhibitors may be used as pharmaceuticals for preventing, monitoring and treating various diseases.
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Bagheri F, Safarian S, Eslaminejad MB, Sheibani N. siRNA-mediated knock-down of DFF45 amplifies doxorubicin therapeutic effects in breast cancer cells. Cell Oncol (Dordr) 2013; 36:515-26. [PMID: 24277473 DOI: 10.1007/s13402-013-0157-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/21/2013] [Indexed: 11/25/2022] Open
Abstract
PURPOSE RNA interference (RNAi) has become a promising tool for cancer therapy. Small interfering RNAs (siRNAs) can synergistically enhance the cell killing effects of drugs used in cancer treatment. Here we examined the effects of siRNA-mediated DNA fragmentation factor 45 (DFF45) gene silencing on breast cancer cell viability, cell cycle arrest, and apoptosis in the presence and absence of doxorubicin. METHODS We designed three siRNAs, which target different regions of the DFF45 mRNA. Gene silencing was confirmed by real time RT-PCR and Western blot analyses. The impact of DFF45 siRNA, doxorubicin, and their combination on the viability, cell cycle and apoptosis of T-47D and MDA-MB-231 breast cancer cells were determined by MTT, PI staining, annexin V binding, caspase-3 activity, DNA laddering, and chromatin condensation assays. RESULTS Based on flow cytometric analyses, we found that silencing of DFF45 alone had little effect on apoptosis, especially in T-47D cells. However, when used in combination with doxorubicin (0.33 μM) a significant increase (P < 0.05) in apoptosis was observed in T-47D and MDA-MB-231 cells, i.e., ~2.5- and 3-fold, respectively. Caspase-3 activity, chromatin condensation, as well as DNA laddering supported increased apoptosis in the combinatorial treatment. Cell cycle arrest in both cell lines occurred at lower levels after siRNA + doxorubicin treatment compared to doxorubicin only. CONCLUSIONS Our data indicate that DFF45 gene silencing, when applied in combination with doxorubicin, may offer a novel therapeutic strategy for the treatment of breast cancer.
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Affiliation(s)
- Fatemeh Bagheri
- Department of Cell and Molecular Biology, School of Biology, College of Science, University of Tehran, Tehran, Iran
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Aleksandrushkina NI, Vanyushin BF. Endonucleases and apoptosis in animals. BIOCHEMISTRY (MOSCOW) 2013; 77:1436-51. [PMID: 23379520 DOI: 10.1134/s0006297912130032] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Endonucleases are the main instruments of obligatory DNA degradation in apoptosis. Many endonucleases have marked processive action; initially they split DNA in chromatin into very large domains, and then they perform in it internucleosomal fragmentation of DNA followed by its hydrolysis to small fragments (oligonucleotides). During apoptosis, DNA of chromatin is attacked by many nucleases that are different in activity, specificity, and order of action. The activity of every endonuclease is regulated in the cell through its own regulatory mechanism (metal ions and other effectors, possibly also S-adenosylmethionine). Apoptosis is impossible without endonucleases as far as it leads to accumulation of unnecessary (defective) DNA, disorders in cell differentiation, embryogenesis, the organism's development, and is accompanied by various severe diseases. The interpretation of the structure and functions of endonucleases and of the nature and action of their modulating effectors is important not only for elucidation of mechanisms of apoptosis, but also for regulation and control of programmed cell death, cell differentiation, and development of organisms.
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Affiliation(s)
- N I Aleksandrushkina
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119991, Russia
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Iglesias-Guimarais V, Gil-Guiñon E, Sánchez-Osuna M, Casanelles E, García-Belinchón M, Comella JX, Yuste VJ. Chromatin collapse during caspase-dependent apoptotic cell death requires DNA fragmentation factor, 40-kDa subunit-/caspase-activated deoxyribonuclease-mediated 3'-OH single-strand DNA breaks. J Biol Chem 2013; 288:9200-15. [PMID: 23430749 DOI: 10.1074/jbc.m112.411371] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Apoptotic nuclear morphology and oligonucleosomal double-strand DNA fragments (also known as DNA ladder) are considered the hallmarks of apoptotic cell death. From a classic point of view, these two processes occur concomitantly. Once activated, DNA fragmentation factor, 40-kDa subunit (DFF40)/caspase-activated DNase (CAD) endonuclease hydrolyzes the DNA into oligonucleosomal-size pieces, facilitating the chromatin package. However, the dogma that the apoptotic nuclear morphology depends on DNA fragmentation has been questioned. Here, we use different cellular models, including MEF CAD(-/-) cells, to unravel the mechanism by which DFF40/CAD influences chromatin condensation and nuclear collapse during apoptosis. Upon apoptotic insult, SK-N-AS cells display caspase-dependent apoptotic nuclear alterations in the absence of internucleosomal DNA degradation. The overexpression of a wild-type form of DFF40/CAD endonuclease, but not of different catalytic-null mutants, restores the cellular ability to degrade the chromatin into oligonucleosomal-length fragments. We show that apoptotic nuclear collapse requires a 3'-OH endonucleolytic activity even though the internucleosomal DNA degradation is impaired. Moreover, alkaline unwinding electrophoresis and In Situ End-Labeling (ISEL)/In Situ Nick Translation (ISNT) assays reveal that the apoptotic DNA damage observed in the DNA ladder-deficient SK-N-AS cells is characterized by the presence of single-strand nicks/breaks. Apoptotic single-strand breaks can be impaired by DFF40/CAD knockdown, abrogating nuclear collapse and disassembly. In conclusion, the highest order of chromatin compaction observed in the later steps of caspase-dependent apoptosis relies on DFF40/CAD-mediated DNA damage by generating 3'-OH ends in single-strand rather than double-strand DNA nicks/breaks.
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Affiliation(s)
- Victoria Iglesias-Guimarais
- Cell Death, Senescence, and Survival Group, Departament de Bioquímica i Biologia Molecular and Institut de Neurociències, Facultat de Medicina, Universitat Autònoma de Barcelona, 08193 Barcelona, Spain
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Fant X, Samejima K, Carvalho A, Ogawa H, Xu Z, Yue Z, Earnshaw WC, Ruchaud S. Use of DT40 conditional-knockout cell lines to study chromosomal passenger protein function. Biochem Soc Trans 2010; 38:1655-9. [PMID: 21118143 PMCID: PMC3428912 DOI: 10.1042/bst0381655] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The CPC [chromosomal passenger complex; INCENP (inner centromere protein), Aurora B kinase, survivin and borealin] is implicated in many mitotic processes. In the present paper we describe how we generated DT40 conditional-knockout cell lines for incenp1 and survivin1 to better understand the role of these CPC subunits in the control of Aurora B kinase activity. These lines enabled us to reassess current knowledge of survivin function and to show that INCENP acts as a rheostat for Aurora B activity.
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Affiliation(s)
- Xavier Fant
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh, EH9 3JR, UK
| | - Kumiko Samejima
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh, EH9 3JR, UK
| | - Ana Carvalho
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh, EH9 3JR, UK
- Ludwig Inst. for Cancer Research, Dept of Cellular & Molecular Medicine, 9500 Gilman Dr., La Jolla, CA 92093-0653, USA
| | - Hiromi Ogawa
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh, EH9 3JR, UK
| | - Zhenjie Xu
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh, EH9 3JR, UK
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, 279 Campus Drive, Stanford, CA 94305-5345, USA
| | - Zuojun Yue
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh, EH9 3JR, UK
- Cell & Developmental Biology, The University of Dundee, Dundee DD1 5EH, United Kingdom
| | - William C. Earnshaw
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh, EH9 3JR, UK
| | - Sandrine Ruchaud
- CNRS USR3151, Station Biologique de Roscoff, place G. Teissier, 29680 Roscoff, FRANCE
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A promoter-hijack strategy for conditional shutdown of multiply spliced essential cell cycle genes. Proc Natl Acad Sci U S A 2008; 105:2457-62. [PMID: 18263736 DOI: 10.1073/pnas.0712083105] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
We describe a method for the isolation of conditional knockouts of essential multiply spliced genes in which the entire body of the gene downstream of the ATG start codon is left untouched but can be switched off rapidly and completely by adding tetracycline to the culture medium. The approach centers on a "promoter-hijack" strategy in which the gene's promoter is replaced with a minimal promoter responsive to the tetracycline-repressible transactivator (tTA). Elsewhere in the genome, a cloned fragment of the gene's promoter is used to drive expression of a tTA. Thus, the gene is essentially regulated by its own promoter but through the intermediary tTA. Using this strategy, we generated a conditional knockout of chromokinesin KIF4A, an important mitotic effector protein whose mRNA is multiply spliced and whose cDNA is highly toxic when overexpressed in cells. We used chicken DT40 cells, but the same strategy should be applicable to ES cells and, eventually, to mice.
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