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Li S, Li J, Peng W, Hao G, Sun J. Characterization of the responses of the caspase 2, 3, 6 and 8 genes to immune challenges and extracellular ATP stimulation in the Japanese flounder (Paralichthys olivaceus). BMC Vet Res 2019; 15:20. [PMID: 30621683 PMCID: PMC6325855 DOI: 10.1186/s12917-018-1763-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Accepted: 12/26/2018] [Indexed: 02/01/2023] Open
Abstract
BACKGROUND Caspases are a family of conserved intracellular cysteine-dependent aspartate-specific cysteine proteases that play important roles in regulating cell death and inflammation. Our previous study revealed the importance of the inflammatory caspase 1 gene in extracellular ATP-mediated immune signaling in Japanese flounder, Paralichthys olivaceus. To explore the potential roles of other caspases in P. olivaceus innate immunity, we extended our study by characterizing of the responses of four additional P. olivaceus caspase genes, termed JfCaspase 2, 3, 6 and 8, to inflammatory challenge and extracellular ATP stimulation. RESULTS Sequence analysis revealed that the domain structures of all the Japanese flounder caspase proteins are evolutionarily conserved. Quantitative real-time PCR analysis showed that the JfCaspase 2, 3, 6 and 8 genes were expressed ubiquitously but at unequal levels in all examined Japanese flounder normal tissues. In addition, the basal gene expression levels of JfCaspase 2, 3, 6 and 8 were higher than those of JfCaspase 1 in both Japanese flounder head kidney macrophages (HKMs) and peripheral blood leukocytes (PBLs). Furthermore, immune challenge experiments showed that the inflammatory stimuli LPS and poly(I:C) significantly modulated the expression of the JfCaspase 2, 3, 6 and 8 genes in Japanese flounder immune cells. Finally, DNA fragmentation, associated with increased extracellular ATP-induced JfCaspase 2, 3, 6 and 8 gene expression and enzymatic activity, was inhibited by the caspase inhibitor Z-VAD-FMK in the HKMs. CONCLUSION Our findings demonstrate broad participation of multiple caspase genes in response to inflammatory stimulation in Japanese flounder immune cells and provide new evidence for the involvement of caspase(s) in extracellular ATP-induced apoptosis in fish.
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Affiliation(s)
- Shuo Li
- Tianjin Key Laboratory of Animal and Plant Resistance, College of Life Sciences, Tianjin Normal University, 393 West Binshui Road, Tianjin, 300387 Xiqing District China
| | - Jiafang Li
- Tianjin Key Laboratory of Animal and Plant Resistance, College of Life Sciences, Tianjin Normal University, 393 West Binshui Road, Tianjin, 300387 Xiqing District China
| | - Weijiao Peng
- Tianjin Key Laboratory of Animal and Plant Resistance, College of Life Sciences, Tianjin Normal University, 393 West Binshui Road, Tianjin, 300387 Xiqing District China
| | - Gaixiang Hao
- Tianjin Key Laboratory of Animal and Plant Resistance, College of Life Sciences, Tianjin Normal University, 393 West Binshui Road, Tianjin, 300387 Xiqing District China
| | - Jinsheng Sun
- Tianjin Key Laboratory of Animal and Plant Resistance, College of Life Sciences, Tianjin Normal University, 393 West Binshui Road, Tianjin, 300387 Xiqing District China
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Kim JY, Garcia-Carbonell R, Yamachika S, Zhao P, Dhar D, Loomba R, Kaufman RJ, Saltiel AR, Karin M. ER Stress Drives Lipogenesis and Steatohepatitis via Caspase-2 Activation of S1P. Cell 2018; 175:133-145.e15. [PMID: 30220454 DOI: 10.1016/j.cell.2018.08.020] [Citation(s) in RCA: 197] [Impact Index Per Article: 32.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 05/11/2018] [Accepted: 08/10/2018] [Indexed: 02/06/2023]
Abstract
Nonalcoholic fatty liver disease (NAFLD) progresses to nonalcoholic steatohepatitis (NASH) in response to elevated endoplasmic reticulum (ER) stress. Whereas the onset of simple steatosis requires elevated de novo lipogenesis, progression to NASH is triggered by accumulation of hepatocyte-free cholesterol. We now show that caspase-2, whose expression is ER-stress inducible and elevated in human and mouse NASH, controls the buildup of hepatic-free cholesterol and triglycerides by activating sterol regulatory element-binding proteins (SREBP) in a manner refractory to feedback inhibition. Caspase-2 colocalizes with site 1 protease (S1P) and cleaves it to generate a soluble active fragment that initiates SCAP-independent SREBP1/2 activation in the ER. Caspase-2 ablation or pharmacological inhibition prevents diet-induced steatosis and NASH progression in ER-stress-prone mice. Caspase-2 inhibition offers a specific and effective strategy for preventing or treating stress-driven fatty liver diseases, whereas caspase-2-generated S1P proteolytic fragments, which enter the secretory pathway, are potential NASH biomarkers.
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Affiliation(s)
- Ju Youn Kim
- Laboratory of Gene Regulation and Signal Transduction, Departments of Pharmacology and Pathology, University of California San Diego, School of Medicine, La Jolla, CA 92093, USA
| | - Ricard Garcia-Carbonell
- Laboratory of Gene Regulation and Signal Transduction, Departments of Pharmacology and Pathology, University of California San Diego, School of Medicine, La Jolla, CA 92093, USA
| | - Shinichiro Yamachika
- Laboratory of Gene Regulation and Signal Transduction, Departments of Pharmacology and Pathology, University of California San Diego, School of Medicine, La Jolla, CA 92093, USA
| | - Peng Zhao
- Division of Endocrinology and Metabolism, Department of Medicine, University of California San Diego, School of Medicine, La Jolla, CA 92093, USA
| | - Debanjan Dhar
- Laboratory of Gene Regulation and Signal Transduction, Departments of Pharmacology and Pathology, University of California San Diego, School of Medicine, La Jolla, CA 92093, USA
| | - Rohit Loomba
- NAFLD Research Center, Division of Gastroenterology, University of California San Diego, School of Medicine, La Jolla, CA 92093, USA
| | - Randal J Kaufman
- Sanford-Burnham-Prebys Medical Discovery Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Alan R Saltiel
- Division of Endocrinology and Metabolism, Department of Medicine, University of California San Diego, School of Medicine, La Jolla, CA 92093, USA
| | - Michael Karin
- Laboratory of Gene Regulation and Signal Transduction, Departments of Pharmacology and Pathology, University of California San Diego, School of Medicine, La Jolla, CA 92093, USA.
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López-García C, Sansregret L, Domingo E, McGranahan N, Hobor S, Birkbak NJ, Horswell S, Grönroos E, Favero F, Rowan AJ, Matthews N, Begum S, Phillimore B, Burrell R, Oukrif D, Spencer-Dene B, Kovac M, Stamp G, Stewart A, Danielsen H, Novelli M, Tomlinson I, Swanton C. BCL9L Dysfunction Impairs Caspase-2 Expression Permitting Aneuploidy Tolerance in Colorectal Cancer. Cancer Cell 2017; 31:79-93. [PMID: 28073006 PMCID: PMC5225404 DOI: 10.1016/j.ccell.2016.11.001] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Revised: 08/05/2016] [Accepted: 10/28/2016] [Indexed: 01/03/2023]
Abstract
Chromosomal instability (CIN) contributes to cancer evolution, intratumor heterogeneity, and drug resistance. CIN is driven by chromosome segregation errors and a tolerance phenotype that permits the propagation of aneuploid genomes. Through genomic analysis of colorectal cancers and cell lines, we find frequent loss of heterozygosity and mutations in BCL9L in aneuploid tumors. BCL9L deficiency promoted tolerance of chromosome missegregation events, propagation of aneuploidy, and genetic heterogeneity in xenograft models likely through modulation of Wnt signaling. We find that BCL9L dysfunction contributes to aneuploidy tolerance in both TP53-WT and mutant cells by reducing basal caspase-2 levels and preventing cleavage of MDM2 and BID. Efforts to exploit aneuploidy tolerance mechanisms and the BCL9L/caspase-2/BID axis may limit cancer diversity and evolution.
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Affiliation(s)
- Carlos López-García
- Translational Cancer Therapeutics Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Laurent Sansregret
- Translational Cancer Therapeutics Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Enric Domingo
- Oxford Centre for Cancer Gene Research, The Wellcome Trust Centre for Human Genetics, Roosevelt Drive, Oxford, OX3 7BN UK; Department of Oncology, University of Oxford, Roosevelt Drive, Oxford OX3 7DQ, UK
| | - Nicholas McGranahan
- Translational Cancer Therapeutics Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK; Translational Cancer Therapeutics Laboratory, University College London Cancer Institute, Paul O'Gorman Building, 72 Huntley Street, London WC2E 6DD, UK
| | - Sebastijan Hobor
- Translational Cancer Therapeutics Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Nicolai Juul Birkbak
- Translational Cancer Therapeutics Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK; Translational Cancer Therapeutics Laboratory, University College London Cancer Institute, Paul O'Gorman Building, 72 Huntley Street, London WC2E 6DD, UK
| | - Stuart Horswell
- Bioinformatics Science Technology Platform, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Eva Grönroos
- Translational Cancer Therapeutics Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Francesco Favero
- Translational Cancer Therapeutics Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK; Cancer System Biology, Centre for Biological Sequence Analysis, Department of Systems Biology, Technical University of Denmark, Lyngby 2800, Denmark
| | - Andrew J Rowan
- Translational Cancer Therapeutics Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Nicholas Matthews
- Advanced Sequencing Facility, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Sharmin Begum
- Advanced Sequencing Facility, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Benjamin Phillimore
- Advanced Sequencing Facility, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Rebecca Burrell
- Translational Cancer Therapeutics Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Dahmane Oukrif
- Research Department of Pathology, University College London Medical School, University Street, London WC1E 6JJ, UK
| | - Bradley Spencer-Dene
- Experimental Histopathology Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Michal Kovac
- Oxford Centre for Cancer Gene Research, The Wellcome Trust Centre for Human Genetics, Roosevelt Drive, Oxford, OX3 7BN UK
| | - Gordon Stamp
- Experimental Histopathology Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Aengus Stewart
- Bioinformatics Science Technology Platform, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Havard Danielsen
- Institute for Cancer Genetics and Informatics, Norwegian Radium Hospital, Oslo University Hospital, Ullernchausseen 70, 0379 Oslo, Norway
| | - Marco Novelli
- Research Department of Pathology, University College London Medical School, University Street, London WC1E 6JJ, UK
| | - Ian Tomlinson
- Oxford Centre for Cancer Gene Research, The Wellcome Trust Centre for Human Genetics, Roosevelt Drive, Oxford, OX3 7BN UK
| | - Charles Swanton
- Translational Cancer Therapeutics Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK; Translational Cancer Therapeutics Laboratory, University College London Cancer Institute, Paul O'Gorman Building, 72 Huntley Street, London WC2E 6DD, UK.
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Venkatesh A, Ma S, Le YZ, Hall MN, Rüegg MA, Punzo C. Activated mTORC1 promotes long-term cone survival in retinitis pigmentosa mice. J Clin Invest 2015; 125:1446-58. [PMID: 25798619 DOI: 10.1172/jci79766] [Citation(s) in RCA: 105] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Accepted: 02/05/2015] [Indexed: 02/06/2023] Open
Abstract
Retinitis pigmentosa (RP) is an inherited photoreceptor degenerative disorder that results in blindness. The disease is often caused by mutations in genes that are specific to rod photoreceptors; however, blindness results from the secondary loss of cones by a still unknown mechanism. Here, we demonstrated that the mammalian target of rapamycin complex 1 (mTORC1) is required to slow the progression of cone death during disease and that constitutive activation of mTORC1 in cones is sufficient to maintain cone function and promote long-term cone survival. Activation of mTORC1 in cones enhanced glucose uptake, retention, and utilization, leading to increased levels of the key metabolite NADPH. Moreover, cone death was delayed in the absence of the NADPH-sensitive cell death protease caspase 2, supporting the contribution of reduced NADPH in promoting cone death. Constitutive activation of mTORC1 preserved cones in 2 mouse models of RP, suggesting that the secondary loss of cones is caused mainly by metabolic deficits and is independent of a specific rod-associated mutation. Together, the results of this study address a longstanding question in the field and suggest that activating mTORC1 in cones has therapeutic potential to prolong vision in RP.
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Abstract
CASP2/caspase 2 plays a role in aging, neurodegeneration, and cancer. The contributions of CASP2 have been attributed to its regulatory role in apoptotic and nonapoptotic processes including the cell cycle, DNA repair, lipid biosynthesis, and regulation of oxidant levels in the cells. Previously, our lab demonstrated CASP2-mediated modulation of autophagy during oxidative stress. Here we report the novel finding that CASP2 is an endogenous repressor of autophagy. Knockout or knockdown of CASP2 resulted in upregulation of autophagy in a variety of cell types and tissues. Reinsertion of Caspase-2 gene (Casp2) in mouse embryonic fibroblast (MEFs) lacking Casp2 (casp2(-/-)) suppresses autophagy, suggesting its role as a negative regulator of autophagy. Loss of CASP2-mediated autophagy involved AMP-activated protein kinase, mechanistic target of rapamycin, mitogen-activated protein kinase, and autophagy-related proteins, indicating the involvement of the canonical pathway of autophagy. The present study also demonstrates an important role for loss of CASP2-induced enhanced reactive oxygen species production as an upstream event in autophagy induction. Additionally, in response to a variety of stressors that induce CASP2-mediated apoptosis, casp2(-/-) cells demonstrate a further upregulation of autophagy compared with wild-type MEFs, and upregulated autophagy provides a survival advantage. In conclusion, we document a novel role for CASP2 as a negative regulator of autophagy, which may provide important insight into the role of CASP2 in various processes including aging, neurodegeneration, and cancer.
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Affiliation(s)
- Meenakshi Tiwari
- Department of Cellular and Structural Biology; University of Texas Health Science Center at San Antonio; South Texas Research Facility; San Antonio, TX USA; Department of Pathology and Laboratory Medicine; All India Institute of Medical Sciences; Patna, India
| | - Lokendra K Sharma
- Department of Cellular and Structural Biology; University of Texas Health Science Center at San Antonio; South Texas Research Facility; San Antonio, TX USA
| | - Difernando Vanegas
- Department of Cellular and Structural Biology; University of Texas Health Science Center at San Antonio; South Texas Research Facility; San Antonio, TX USA
| | - Danielle A Callaway
- Department of Cellular and Structural Biology; University of Texas Health Science Center at San Antonio; South Texas Research Facility; San Antonio, TX USA
| | - Yidong Bai
- Department of Cellular and Structural Biology; University of Texas Health Science Center at San Antonio; South Texas Research Facility; San Antonio, TX USA
| | - James D Lechleiter
- Department of Cellular and Structural Biology; University of Texas Health Science Center at San Antonio; South Texas Research Facility; San Antonio, TX USA
| | - Brian Herman
- Department of Cellular and Structural Biology; University of Texas Health Science Center at San Antonio; South Texas Research Facility; San Antonio, TX USA
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Semighini CP, Averette AF, Perfect JR, Heitman J. Deletion of Cryptococcus neoformans AIF ortholog promotes chromosome aneuploidy and fluconazole-resistance in a metacaspase-independent manner. PLoS Pathog 2011; 7:e1002364. [PMID: 22114551 PMCID: PMC3219705 DOI: 10.1371/journal.ppat.1002364] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2011] [Accepted: 09/22/2011] [Indexed: 11/18/2022] Open
Abstract
Apoptosis is a form of programmed cell death critical for development and homeostasis in multicellular organisms. Apoptosis-like cell death (ALCD) has been described in several fungi, including the opportunistic human pathogen Cryptococcus neoformans. In addition, capsular polysaccharides of C. neoformans are known to induce apoptosis in host immune cells, thereby contributing to its virulence. Our goals were to characterize the apoptotic signaling cascade in C. neoformans as well as its unique features compared to the host machinery to exploit the endogenous fungal apoptotic pathways as a novel antifungal strategy in the future. The dissection of apoptotic pathways revealed that apoptosis-inducing factor (Aif1) and metacaspases (Mca1 and Mca2) are independently required for ALCD in C. neoformans. We show that the apoptotic pathways are required for cell fusion and sporulation during mating, indicating that apoptosis may occur during sexual development. Previous studies showed that antifungal drugs induce ALCD in fungi and that C. neoformans adapts to high concentrations of the antifungal fluconazole (FLC) by acquisition of aneuploidy, especially duplication of chromosome 1 (Chr1). Disruption of aif1, but not the metacaspases, stimulates the emergence of aneuploid subpopulations with Chr1 disomy that are resistant to fluconazole (FLCR) in vitro and in vivo. FLCR isolates in the aif1 background are stable in the absence of the drug, while those in the wild-type background readily revert to FLC sensitivity. We propose that apoptosis orchestrated by Aif1 might eliminate aneuploid cells from the population and defects in this pathway contribute to the selection of aneuploid FLCR subpopulations during treatment. Aneuploid clinical isolates with disomies for chromosomes other than Chr1 exhibit reduced AIF1 expression, suggesting that inactivation of Aif1 might be a novel aneuploidy-tolerating mechanism in fungi that facilitates the selection of antifungal drug resistance. Fungal pathogens can cause life-threatening diseases, and the infections that they cause are notoriously difficult to treat. Despite the availability of antifungal drugs, most inhibit fungal growth but do not consistently or efficiently eliminate the pathogen. In addition, fungal cells are very similar to human cells, and therefore, many of the available antifungal agents have toxic side effects. Thus, more efficient drugs with less adverse effects are clearly needed. We investigated apoptosis, a process in which cells become programmed to commit suicide, in the pathogenic fungus Cryptococcus neoformans. We studied genes that regulate apoptosis in C. neoformans and, after inactivating three genes involved in this pathway, we observed defects in sexual reproduction. Such mating defects decrease the production of spores, which are inhaled and cause cryptococcal disease. We also showed that the absence of one investigated apoptotic gene, aif1, resulted in the selection of antifungal-resistant pathogens (when the fungal cells no longer respond to the drug), which makes treatment of the disease more difficult. The discovery of drugs that kill fungal cells specifically without affecting the cells of the patient being treated holds great potential. Therefore, triggering apoptosis should be further investigated as a new approach to treat fungal pathogens.
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Affiliation(s)
- Camile P. Semighini
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Anna F. Averette
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - John R. Perfect
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
- Department of Medicine, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Joseph Heitman
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
- Department of Medicine, Duke University Medical Center, Durham, North Carolina, United States of America
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina, United States of America
- * E-mail:
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Mahoney DJ, Lefebvre C, Allan K, Brun J, Sanaei CA, Baird S, Pearce N, Grönberg S, Wilson B, Prakesh M, Aman A, Isaac M, Mamai A, Uehling D, Al-Awar R, Falls T, Alain T, Stojdl DF. Virus-tumor interactome screen reveals ER stress response can reprogram resistant cancers for oncolytic virus-triggered caspase-2 cell death. Cancer Cell 2011; 20:443-56. [PMID: 22014571 DOI: 10.1016/j.ccr.2011.09.005] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2011] [Revised: 08/02/2011] [Accepted: 09/13/2011] [Indexed: 10/16/2022]
Abstract
To identify therapeutic opportunities for oncolytic viral therapy, we conducted genome-wide RNAi screens to search for host factors that modulate rhabdoviral oncolysis. Our screens uncovered the endoplasmic reticulum (ER) stress response pathways as important modulators of rhabdovirus-mediated cytotoxicity. Further investigation revealed an unconventional mechanism whereby ER stress response inhibition preconditioned cancer cells, which sensitized them to caspase-2-dependent apoptosis induced by a subsequent rhabdovirus infection. Importantly, this mechanism was tumor cell specific, selectively increasing potency of the oncolytic virus by up to 10,000-fold. In vivo studies using a small molecule inhibitor of IRE1α showed dramatically improved oncolytic efficacy in resistant tumor models. Our study demonstrates proof of concept for using functional genomics to improve biotherapeutic agents for cancer.
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Affiliation(s)
- Douglas J Mahoney
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario K1H 8L1, Canada
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Lamers F, van der Ploeg I, Schild L, Ebus ME, Koster J, Hansen BR, Koch T, Versteeg R, Caron HN, Molenaar JJ. Knockdown of survivin (BIRC5) causes apoptosis in neuroblastoma via mitotic catastrophe. Endocr Relat Cancer 2011; 18:657-68. [PMID: 21859926 DOI: 10.1530/erc-11-0207] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
BIRC5 (survivin) is one of the genes located on chromosome arm 17q in the region that is often gained in neuroblastoma. BIRC5 is a protein in the intrinsic apoptotic pathway that interacts with XIAP and DIABLO leading to caspase-3 and caspase-9 inactivation. BIRC5 is also involved in stabilizing the microtubule-kinetochore dynamics. Based on the Affymetrix mRNA expression data, we here show that BIRC5 expression is strongly upregulated in neuroblastoma compared with normal tissues, adult malignancies, and non-malignant fetal adrenal neuroblasts. The over-expression of BIRC5 correlates with an unfavorable prognosis independent of the presence of 17q gain. Silencing of BIRC5 in neuroblastoma cell lines by various antisense molecules resulted in massive apoptosis as measured by PARP cleavage and FACS analysis. As both the intrinsic apoptotic pathway and the chromosomal passenger complex can be therapeutically targeted, we investigated in which of them BIRC5 exerted its essential anti-apoptotic role. Immunofluorescence analysis of neuroblastoma cells after BIRC5 silencing showed formation of multinucleated cells indicating mitotic catastrophe, which leads to apoptosis via P53 and CASP2. We show that BIRC5 silencing indeed resulted in activation of P53 and we could rescue apoptosis by CASP2 inhibition. We conclude that BIRC5 stabilizes the microtubules in the chromosomal passenger complex in neuroblastoma and that the apoptotic response results from mitotic catastrophe, which makes BIRC5 an interesting target for therapy.
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Affiliation(s)
- Fieke Lamers
- Department of Oncogenomics, Academic Medical Center, University of Amsterdam, Meibergdreef 15, PO Box 22700, 1105 AZ Amsterdam, The Netherlands
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Abstract
Brucella species are Gram-negative, facultative intracellular bacteria that cause zoonotic brucellosis. Survival and replication inside macrophages is critical for establishment of chronic Brucella infection. Virulent smooth B. abortus strain 2308 inhibits programmed macrophage cell death and replicates inside macrophages. Cattle B. abortus vaccine strain RB51 is an attenuated rough, lipopolysaccharide O antigen-deficient mutant derived from smooth strain 2308. B. abortus rough mutant RA1 contains a single wboA gene mutation in strain 2308. Our studies demonstrated that live RB51 and RA1, but not strain 2308 or heat-killed Brucella, induced both apoptotic and necrotic cell death in murine RAW264.7 macrophages and bone marrow derived macrophages. The same phenomenon was also observed in primary mouse peritoneal macrophages from mice immunized intraperitoneally with vaccine strain RB51 using the same dose as regularly performed in protection studies. Programmed macrophage cell death induced by RB51 and RA1 was inhibited by a caspase-2 inhibitor (Z-VDVAD-FMK). Caspase-2 enzyme activation and cleavage were observed at the early infection stage in macrophages infected with RB51 and RA1 but not strain 2308. The inhibition of macrophage cell death promoted the survival of rough Brucella cells inside macrophages. The critical role of caspase-2 in mediating rough B. abortus induced macrophage cell death was confirmed using caspase-2 specific shRNA. The mitochondrial apoptosis pathway was activated in macrophages infected with rough B. abortus as demonstrated by increase in mitochondrial membrane permeability and the release of cytochrome c to cytoplasm in macrophages infected with rough Brucella. These results demonstrate that rough B. abortus strains RB51 and RA1 induce apoptotic and necrotic murine macrophage cell death that is mediated by caspase-2. The biological relevance of Brucella O antigen and caspase-2-mediated macrophage cell death in Brucella pathogenesis and protective Brucella immunity is discussed.
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Affiliation(s)
- Fang Chen
- Unit for Laboratory Animal Medicine and Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Yongqun He
- Unit for Laboratory Animal Medicine and Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
- * E-mail:
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