1
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Ceramide-induced integrated stress response overcomes Bcl-2 inhibitor resistance in acute myeloid leukemia. Blood 2022; 139:3737-3751. [PMID: 35443029 PMCID: PMC9642852 DOI: 10.1182/blood.2021013277] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Accepted: 04/04/2022] [Indexed: 11/24/2022] Open
Abstract
Enhancing cellular ceramide levels in AML activates protein kinase R
to induce the integrated stress response. The ISR induces the BH3-only protein Noxa, causing degradation of
Mcl-1 and sensitization of AML to Bcl-2 inhibition.
Inducing cell death by the sphingolipid ceramide is a potential anticancer
strategy, but the underlying mechanisms remain poorly defined. In this study,
triggering an accumulation of ceramide in acute myeloid leukemia (AML) cells by
inhibition of sphingosine kinase induced an apoptotic integrated stress response
(ISR) through protein kinase R–mediated activation of the master
transcription factor ATF4. This effect led to transcription of the BH3-only
protein Noxa and degradation of the prosurvival Mcl-1 protein on which AML cells
are highly dependent for survival. Targeting this novel ISR pathway, in
combination with the Bcl-2 inhibitor venetoclax, synergistically killed primary
AML blasts, including those with venetoclax-resistant mutations, as well as
immunophenotypic leukemic stem cells, and reduced leukemic engraftment in
patient-derived AML xenografts. Collectively, these findings provide mechanistic
insight into the anticancer effects of ceramide and preclinical evidence for new
approaches to augment Bcl-2 inhibition in the therapy of AML and other cancers
with high Mcl-1 dependency.
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2
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Revathidevi S, Munirajan AK. Akt in cancer: Mediator and more. Semin Cancer Biol 2019; 59:80-91. [PMID: 31173856 DOI: 10.1016/j.semcancer.2019.06.002] [Citation(s) in RCA: 379] [Impact Index Per Article: 75.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Revised: 04/29/2019] [Accepted: 06/03/2019] [Indexed: 02/06/2023]
Abstract
Akt is a serine/threonine kinase and it participates in the key role of the PI3K signaling pathway. The Akt can be activated by a wide range of growth signals and the biochemical mechanisms leading to Akt activation are well defined. Once activated, Akt modulates the function of many downstream proteins involved in cellular survival, proliferation, migration, metabolism, and angiogenesis. The Akt is a central node of many signaling pathways and it is frequently deregulated in many types of human cancers. In this review, we provide an overview of Akt function and its role in the hallmarks of human cancer. We also discussed various mechanisms of Akt dysregulation in cancers, including epigenetic modifications like methylation, post-transcriptional non-coding RNAs-mediated regulation, and the overexpression and mutation.
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Affiliation(s)
- Sundaramoorthy Revathidevi
- Department of Genetics, Dr. ALM PG Institute of Basic Medical Sciences, University of Madras, Taramani Campus, Chennai, 113, Tamil Nadu, India
| | - Arasambattu Kannan Munirajan
- Department of Genetics, Dr. ALM PG Institute of Basic Medical Sciences, University of Madras, Taramani Campus, Chennai, 113, Tamil Nadu, India.
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3
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Huang P, Li X, Meng Y, Yuan B, Liu T, Jiao M, Wang X, Liu Y, Yin H. Interleukin-33 regulates hematopoietic stem cell regeneration after radiation injury. Stem Cell Res Ther 2019; 10:123. [PMID: 30999922 PMCID: PMC6471888 DOI: 10.1186/s13287-019-1221-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Revised: 02/21/2019] [Accepted: 03/25/2019] [Indexed: 12/15/2022] Open
Abstract
Background IL-33 is a pleiotropic cytokine of the IL-1 family, which has been reported to implicate in both innate and adaptive immune responses. Recent studies suggest IL-33 is crucial for regulation of myelopoiesis and myeloid cell activity. Here, we explore the potential effect of IL-33 against hematopoietic injury after total body irradiation (TBI). Methods C57BL/6 mice were irradiated with a sublethal dose of radiation (600 cGy) and treated with IL-33 at a dose of 3 μg/dose i.p. once a day for seven consecutive days. H&E staining was used to determine the bone marrow cellularity. A flow cytometer was used to quantify the hematopoietic stem cell (HSC) population, cell proliferation, and apoptosis. The colony-forming assay was used to evaluate the clonogenic function of HSCs. RT-qPCR was used to determine the expression of apoptosis-associated genes. Results Bone marrow HSCs from wild-type mice expressed functional IL-33 receptor (ST2), and treatment with IL-33 promoted the recovery of the HSC pool in vivo and improved the survival of mice after TBI. Conversely, mice with ST2 deficiency showed decreased HSC regeneration and mouse survival after TBI. Of note, IL-33 reduced radiation-induced apoptosis of HSCs and mediated this effect through repression of the p53-PUMA pathway. Conclusions IL-33 regulates HSC regeneration after myelosuppressive injury through protecting HSCs from apoptosis and enhancing proliferation of the surviving HSCs.
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Affiliation(s)
- Ping Huang
- Department of Microbiology and Immunology, Guangdong Pharmaceutical University, Guangzhou, 510006, China
| | - Xiangyong Li
- Institute of Biochemistry and Molecular Biology, Guangdong Medical University, Zhanjiang, 524023, China
| | - Ying Meng
- Department of Microbiology and Immunology, Guangdong Pharmaceutical University, Guangzhou, 510006, China
| | - Baohong Yuan
- Department of Microbiology and Immunology, Guangdong Pharmaceutical University, Guangzhou, 510006, China
| | - Tao Liu
- Guangdong Provincial Key Laboratory of Pharmaceutical Bioactive Substances, Guangdong Pharmaceutical University, Guangzhou, 510006, China
| | - Mengya Jiao
- Guangdong Provincial Key Laboratory of Pharmaceutical Bioactive Substances, Guangdong Pharmaceutical University, Guangzhou, 510006, China
| | - Xiaodi Wang
- Department of Microbiology and Immunology, Guangdong Pharmaceutical University, Guangzhou, 510006, China
| | - Yunjun Liu
- School of Pharmacy, Guangdong Pharmaceutical University, Guangzhou, 510006, China.
| | - Hui Yin
- Department of Microbiology and Immunology, Guangdong Pharmaceutical University, Guangzhou, 510006, China. .,Guangdong Provincial Key Laboratory of Pharmaceutical Bioactive Substances, Guangdong Pharmaceutical University, Guangzhou, 510006, China.
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4
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Dong L, Reljic B, Cheung JG, Ng ES, Lindqvist LM, Elefanty AG, Vaux DL, Tran H. In the absence of apoptosis, myeloid cells arrest when deprived of growth factor, but remain viable by consuming extracellular glucose. Cell Death Differ 2019; 26:2074-2085. [PMID: 30770875 DOI: 10.1038/s41418-019-0275-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Revised: 12/17/2018] [Accepted: 12/20/2018] [Indexed: 11/10/2022] Open
Abstract
Withdrawal of the growth factor interleukin-3 (IL-3) from IL-3-dependent myeloid cells causes them to undergo Bax/Bak1-dependent apoptosis, whereas factor-deprived Bax-/-Bak1-/- cells remain viable, but arrest and shrink. It was reported that withdrawal of IL-3 from Bax-/-Bak1-/- cells caused decreased expression of the glucose transporter Glut1, leading to reduced glucose uptake, so that arrested cells required Atg5-dependent autophagy for long-term survival. In other cell types, a decrease in Glut1 is mediated by the thioredoxin-interacting protein (Txnip), which is induced in IL-3-dependent myeloid cells when growth factor is removed. We mutated Atg5 and Txnip by CRISPR/Cas9 and found that Atg5-dependent autophagy was not necessary for the long-term viability of cycling or arrested Bax-/-Bak1-/- cells, and that Txnip was not required for the decrease in Glut1 expression in response to IL-3 withdrawal. Surprisingly, Atg5-deficient Bax/Bak1 double mutant cells survived for several weeks in medium supplemented with 10% fetal bovine serum (FBS), without high concentrations of added glucose or glutamine. When serum was withdrawn, the provision of an equivalent amount of glucose present in 10% FBS (~0.5 mM) was sufficient to support cell survival for more than a week, in the presence or absence of IL-3. Thus, Bax-/-Bak1-/- myeloid cells deprived of growth factor consume extracellular glucose to maintain long-term viability, without a requirement for Atg5-dependent autophagy.
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Affiliation(s)
- Li Dong
- The Walter and Eliza Hall Institute of Medical Research and the Department of Medical Biology, University of Melbourne, Melbourne, VIC, Australia
| | - Boris Reljic
- The Walter and Eliza Hall Institute of Medical Research and the Department of Medical Biology, University of Melbourne, Melbourne, VIC, Australia
| | - Jen G Cheung
- The Walter and Eliza Hall Institute of Medical Research and the Department of Medical Biology, University of Melbourne, Melbourne, VIC, Australia
| | - Elizabeth S Ng
- Murdoch Childrens Research Institute, The Royal Children's Hospital, Parkville, VIC, Australia
| | - Lisa M Lindqvist
- The Walter and Eliza Hall Institute of Medical Research and the Department of Medical Biology, University of Melbourne, Melbourne, VIC, Australia
| | - Andrew G Elefanty
- Murdoch Childrens Research Institute, The Royal Children's Hospital, Parkville, VIC, Australia.,Department of Anatomy and Developmental Biology, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, VIC, Australia
| | - David L Vaux
- The Walter and Eliza Hall Institute of Medical Research and the Department of Medical Biology, University of Melbourne, Melbourne, VIC, Australia
| | - Hoanh Tran
- The Walter and Eliza Hall Institute of Medical Research and the Department of Medical Biology, University of Melbourne, Melbourne, VIC, Australia.
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5
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Song T, Wang P, Yu X, Wang A, Chai G, Fan Y, Zhang Z. Systems analysis of phosphorylation-regulated Bcl-2 interactions establishes a model to reconcile the controversy over the significance of Bcl-2 phosphorylation. Br J Pharmacol 2019; 176:491-504. [PMID: 30500985 PMCID: PMC6329625 DOI: 10.1111/bph.14555] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 10/23/2018] [Accepted: 10/25/2018] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND AND PURPOSE The biological significance of the multi-site phosphorylation of Bcl-2 at its loop region (T69, S70 and S87) has remained controversial for decades. This is a major obstacle for understanding apoptosis and anti-tumour drug development. EXPERIMENTAL APPROACH We established a mathematical model into which a phosphorylation and de-phosphorylation process of Bcl-2 was integrated. Paclitaxel-treated breast cancer cells were used as experimental models. Changes in the kinetics of binding with its critical partners, induced by phosphorylation of Bcl-2 were experimentally obtained by surface plasmon resonance, using a phosphorylation-mimicking mutant EEE-Bcl-2 (T69E, S70E and S87E). KEY RESULTS Mathematical simulations combined with experimental validation showed that phosphorylation regulates Bcl-2 with different dynamics depending on the extent of Bcl-2 phosphorylation and the phosphorylated Bcl-2-induced changes in binding kinetics. In response to Bcl-2 homology 3 (BH3)-only protein Bmf stress, Bcl-2 phosphorylation switched from diminishing to enhancing the Bcl-2 anti-apoptotic ability with increased phosphorylation of Bcl-2, and the turning point was 50% Bcl-2 phosphorylation induced by 0.2 μM paclitaxel treatment. In contrast, Bcl-2 phosphorylation enhanced the anti-apoptotic ability of Bcl-2 towards other BH3-only proteins Bim, Bad and Puma, throughout the entire phosphorylation procedure. CONCLUSIONS AND IMPLICATIONS The model could accurately predict the effects of anti-tumour drugs that involve the Bcl-2 family pathway, as shown with ABT-199 or etoposide.
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Affiliation(s)
- Ting Song
- State Key Laboratory of Fine Chemicals, School of ChemistryDalian University of TechnologyDalianChina
| | - Peiran Wang
- State Key Laboratory of Fine Chemicals, School of ChemistryDalian University of TechnologyDalianChina
| | - Xiaoyan Yu
- School of Life Science and TechnologyDalian University of TechnologyDalianChina
| | - Anhui Wang
- School of Innovation ExperimentDalian University of TechnologyDalianChina
| | - Gaobo Chai
- School of Life Science and TechnologyDalian University of TechnologyDalianChina
| | - Yudan Fan
- School of Life Science and TechnologyDalian University of TechnologyDalianChina
| | - Zhichao Zhang
- State Key Laboratory of Fine Chemicals, School of ChemistryDalian University of TechnologyDalianChina
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6
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Schubert F, Rapp J, Brauns-Schubert P, Schlicher L, Stock K, Wissler M, Weiß M, Charvet C, Borner C, Maurer U. Requirement of GSK-3 for PUMA induction upon loss of pro-survival PI3K signaling. Cell Death Dis 2018; 9:470. [PMID: 29686375 PMCID: PMC5913275 DOI: 10.1038/s41419-018-0502-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Revised: 03/09/2018] [Accepted: 03/15/2018] [Indexed: 02/06/2023]
Abstract
Growth factor withdrawal induces rapid apoptosis via mitochondrial outer membrane permeabilization. We had previously observed that cell death of IL-3-dependent Ba/F3 cells, induced by removal of the growth factor, required the activity of the kinase GSK-3. Employing CRISPR/Cas9-mediated gene knockout, we aimed to identify pro-apoptotic GSK-3 regulated factors in this process. Knockout of either Puma or Bim demonstrated that the induction of Puma, but not Bim, was crucial for apoptosis induced by IL-3 deprivation. Thus, we aimed at identifying the GSK-3-dependent PUMA regulator. Loss of FOXO3A reduced the induction of Puma, while additional loss of p53 completely repressed induction upon growth factor withdrawal. A constitutively active mutant of FOXO3A, which cannot be controlled by AKT directly, still required active GSK-3 for the full transcriptional induction of Puma and cell death upon IL-3 withdrawal. Thus, the suppression of GSK-3 is the key function of PI3K signaling in order to prevent the induction of Puma by FOXO3A and p53 and thereby apoptosis upon growth factor withdrawal.
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Affiliation(s)
- Florian Schubert
- Institute of Molecular Medicine and Cell Research, Faculty of Medicine, Albert-Ludwigs-University of Freiburg, Freiburg, Germany.,Spemann Graduate School of Biology and Medicine (SGBM), Albert-Ludwigs-University of Freiburg, Freiburg, Germany.,Faculty of Biology, University of Freiburg, Schänzlestrasse 1, 79104, Freiburg, Germany
| | - Juliane Rapp
- Institute of Molecular Medicine and Cell Research, Faculty of Medicine, Albert-Ludwigs-University of Freiburg, Freiburg, Germany.,Faculty of Biology, University of Freiburg, Schänzlestrasse 1, 79104, Freiburg, Germany
| | - Prisca Brauns-Schubert
- Institute of Molecular Medicine and Cell Research, Faculty of Medicine, Albert-Ludwigs-University of Freiburg, Freiburg, Germany.,Spemann Graduate School of Biology and Medicine (SGBM), Albert-Ludwigs-University of Freiburg, Freiburg, Germany.,Faculty of Biology, University of Freiburg, Schänzlestrasse 1, 79104, Freiburg, Germany.,BIOSS, Centre for Biological Signaling Studies, Hebelstrasse 2, 79104, Freiburg, Germany
| | - Lisa Schlicher
- Institute of Molecular Medicine and Cell Research, Faculty of Medicine, Albert-Ludwigs-University of Freiburg, Freiburg, Germany.,Spemann Graduate School of Biology and Medicine (SGBM), Albert-Ludwigs-University of Freiburg, Freiburg, Germany.,Faculty of Biology, University of Freiburg, Schänzlestrasse 1, 79104, Freiburg, Germany.,BIOSS, Centre for Biological Signaling Studies, Hebelstrasse 2, 79104, Freiburg, Germany
| | - Kerstin Stock
- Institute of Molecular Medicine and Cell Research, Faculty of Medicine, Albert-Ludwigs-University of Freiburg, Freiburg, Germany.,Faculty of Biology, University of Freiburg, Schänzlestrasse 1, 79104, Freiburg, Germany
| | - Manuela Wissler
- Institute of Molecular Medicine and Cell Research, Faculty of Medicine, Albert-Ludwigs-University of Freiburg, Freiburg, Germany
| | - Martina Weiß
- Institute of Molecular Medicine and Cell Research, Faculty of Medicine, Albert-Ludwigs-University of Freiburg, Freiburg, Germany
| | - Céline Charvet
- Functional Genomics and Cancer, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR 7104, Université de Strasbourg, 1 rue Laurent Fries, Illkirch, 67404, France
| | - Christoph Borner
- Institute of Molecular Medicine and Cell Research, Faculty of Medicine, Albert-Ludwigs-University of Freiburg, Freiburg, Germany.,Spemann Graduate School of Biology and Medicine (SGBM), Albert-Ludwigs-University of Freiburg, Freiburg, Germany.,BIOSS, Centre for Biological Signaling Studies, Hebelstrasse 2, 79104, Freiburg, Germany
| | - Ulrich Maurer
- Institute of Molecular Medicine and Cell Research, Faculty of Medicine, Albert-Ludwigs-University of Freiburg, Freiburg, Germany. .,Spemann Graduate School of Biology and Medicine (SGBM), Albert-Ludwigs-University of Freiburg, Freiburg, Germany. .,BIOSS, Centre for Biological Signaling Studies, Hebelstrasse 2, 79104, Freiburg, Germany.
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7
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Apoptosis in megakaryocytes and platelets: the life and death of a lineage. Blood 2017; 131:605-610. [PMID: 29259001 DOI: 10.1182/blood-2017-11-742684] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Accepted: 12/03/2017] [Indexed: 12/17/2022] Open
Abstract
Despite their profoundly different cellular composition, size, and function, megakaryocytes and platelets both depend on restraint of the intrinsic (or "mitochondrial") apoptosis pathway by BCL-2 family prosurvival proteins for their development and viability. Activation of the pathway contributes to the clearance of megakaryocytes following platelet shedding and constrains platelet lifespan in the circulation. Important questions remain as to how apoptosis is initiated in these cells at steady state and in response to pathophysiological insults.
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8
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Brown LM, Hanna DT, Khaw SL, Ekert PG. Dysregulation of BCL-2 family proteins by leukemia fusion genes. J Biol Chem 2017; 292:14325-14333. [PMID: 28717011 DOI: 10.1074/jbc.r117.799056] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The genomic lesions that characterize acute lymphoblastic leukemia in childhood include recurrent translocations that result in the expression of fusion proteins that typically involve genes encoding tyrosine kinases, cytokine receptors, and transcription factors. These genetic rearrangements confer phenotypic hallmarks of malignant transformation, including unrestricted proliferation and a relative resistance to apoptosis. In this Minireview, we discuss the molecular mechanisms that link these fusions to the control of cell death. We examine how these fusion genes dysregulate the BCL-2 family of proteins, preventing activation of the apoptotic effectors, BAX and BAK, and promoting cell survival.
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Affiliation(s)
- Lauren M Brown
- From the Murdoch Children's Research Institute.,Department of Paediatrics, University of Melbourne
| | - Diane T Hanna
- the Royal Children's Hospital, and.,the Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia
| | - Seong L Khaw
- From the Murdoch Children's Research Institute.,the Royal Children's Hospital, and.,the Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia
| | - Paul G Ekert
- From the Murdoch Children's Research Institute, .,the Royal Children's Hospital, and
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9
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Cycloheximide Can Induce Bax/Bak Dependent Myeloid Cell Death Independently of Multiple BH3-Only Proteins. PLoS One 2016; 11:e0164003. [PMID: 27806040 PMCID: PMC5091851 DOI: 10.1371/journal.pone.0164003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Accepted: 09/19/2016] [Indexed: 01/25/2023] Open
Abstract
Apoptosis mediated by Bax or Bak is usually thought to be triggered by BH3-only members of the Bcl-2 protein family. BH3-only proteins can directly bind to and activate Bax or Bak, or indirectly activate them by binding to anti-apoptotic Bcl-2 family members, thereby relieving their inhibition of Bax and Bak. Here we describe a third way of activation of Bax/Bak dependent apoptosis that does not require triggering by multiple BH3-only proteins. In factor dependent myeloid (FDM) cell lines, cycloheximide induced apoptosis by a Bax/Bak dependent mechanism, because Bax-/-Bak-/- lines were profoundly resistant, whereas FDM lines lacking one or more genes for BH3-only proteins remained highly sensitive. Addition of cycloheximide led to the rapid loss of Mcl-1 but did not affect the expression of other Bcl-2 family proteins. In support of these findings, similar results were observed by treating FDM cells with the CDK inhibitor, roscovitine. Roscovitine reduced Mcl-1 abundance and caused Bax/Bak dependent cell death, yet FDM lines lacking one or more genes for BH3-only proteins remained highly sensitive. Therefore Bax/Bak dependent apoptosis can be regulated by the abundance of anti-apoptotic Bcl-2 family members such as Mcl-1, independently of several known BH3-only proteins.
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10
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Papaianni E, El Maadidi S, Schejtman A, Neumann S, Maurer U, Marino-Merlo F, Mastino A, Borner C. Phylogenetically Distant Viruses Use the Same BH3-Only Protein Puma to Trigger Bax/Bak-Dependent Apoptosis of Infected Mouse and Human Cells. PLoS One 2015; 10:e0126645. [PMID: 26030884 PMCID: PMC4452691 DOI: 10.1371/journal.pone.0126645] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Accepted: 04/04/2015] [Indexed: 12/12/2022] Open
Abstract
Viruses can trigger apoptosis of infected host cells if not counteracted by cellular or viral anti-apoptotic proteins. These protective proteins either inhibit the activation of caspases or they act as Bcl-2 homologs to prevent Bax/Bak-mediated outer mitochondrial membrane permeabilization (MOMP). The exact mechanism by which viruses trigger MOMP has however remained enigmatic. Here we use two distinct types of viruses, a double stranded DNA virus, herpes simplex virus-1 (HSV-1) and a positive sense, single stranded RNA virus, Semliki Forest virus (SFV) to show that the BH3-only protein Puma is the major mediator of virus-induced Bax/Bak activation and MOMP induction. Indeed, when Puma was genetically deleted or downregulated by shRNA, mouse embryonic fibroblasts and IL-3-dependent monocytes as well as human colon carcinoma cells were as resistant to virus-induced apoptosis as their Bax/Bak double deficient counterparts (Bax/Bak-/-). Puma protein expression started to augment after 2 h postinfection with both viruses. Puma mRNA levels increased as well, but this occurred after apoptosis initiation (MOMP) because it was blocked in cells lacking Bax/Bak or overexpressing Bcl-xL. Moreover, none of the classical Puma transcription factors such as p53, p73 or p65 NFκB were involved in HSV-1-induced apoptosis. Our data suggest that viruses use a Puma protein-dependent mechanism to trigger MOMP and apoptosis in host cells.
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Affiliation(s)
- Emanuela Papaianni
- Department of Biological and Environmental Sciences, University of Messina, Via F. Stagno d’Alcontres 31, I-98166, Messina, Italy
- The Institute of Translational Pharmacology, CNR, Via Fosso del Cavaliere 100, I-00133, Rome, Italy
- Institute of Molecular Medicine and Cell Research, Albert Ludwigs University of Freiburg, Stefan Meier Strasse 17, D-79104, Freiburg, Germany
| | - Souhayla El Maadidi
- Institute of Molecular Medicine and Cell Research, Albert Ludwigs University of Freiburg, Stefan Meier Strasse 17, D-79104, Freiburg, Germany
- Faculty of Biology, Albert Ludwigs University of Freiburg, Schänzlestrasse 1, D-79104, Freiburg, Germany
| | - Andrea Schejtman
- Institute of Molecular Medicine and Cell Research, Albert Ludwigs University of Freiburg, Stefan Meier Strasse 17, D-79104, Freiburg, Germany
- IMBS Program between Albert Ludwigs University of Freiburg, Freiburg, Germany, and University of Buenos Aires, Buenos Aires, Argentina
| | - Simon Neumann
- Institute of Molecular Medicine and Cell Research, Albert Ludwigs University of Freiburg, Stefan Meier Strasse 17, D-79104, Freiburg, Germany
| | - Ulrich Maurer
- Institute of Molecular Medicine and Cell Research, Albert Ludwigs University of Freiburg, Stefan Meier Strasse 17, D-79104, Freiburg, Germany
- Spemann Graduate School of Biology and Medicine (SGBM), Albert Ludwigs University of Freiburg, Albertstrasse 19a, D-79104, Freiburg, Germany
- BIOSS, Centre for Biological Signaling Studies, Hebelstrasse 2, D-79104, Freiburg, Germany
| | - Francesca Marino-Merlo
- Department of Biological and Environmental Sciences, University of Messina, Via F. Stagno d’Alcontres 31, I-98166, Messina, Italy
| | - Antonio Mastino
- Department of Biological and Environmental Sciences, University of Messina, Via F. Stagno d’Alcontres 31, I-98166, Messina, Italy
- The Institute of Translational Pharmacology, CNR, Via Fosso del Cavaliere 100, I-00133, Rome, Italy
- * E-mail: (AM); (CB)
| | - Christoph Borner
- Institute of Molecular Medicine and Cell Research, Albert Ludwigs University of Freiburg, Stefan Meier Strasse 17, D-79104, Freiburg, Germany
- Spemann Graduate School of Biology and Medicine (SGBM), Albert Ludwigs University of Freiburg, Albertstrasse 19a, D-79104, Freiburg, Germany
- BIOSS, Centre for Biological Signaling Studies, Hebelstrasse 2, D-79104, Freiburg, Germany
- * E-mail: (AM); (CB)
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11
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Brumatti G, Salmanidis M, Kok CH, Bilardi RA, Sandow JJ, Silke N, Mason K, Visser J, Jabbour AM, Glaser SP, Okamoto T, Bouillet P, D'Andrea RJ, Ekert PG. HoxA9 regulated Bcl-2 expression mediates survival of myeloid progenitors and the severity of HoxA9-dependent leukemia. Oncotarget 2014; 4:1933-47. [PMID: 24177192 PMCID: PMC3875760 DOI: 10.18632/oncotarget.1306] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Deregulated expression of Hox genes such as HoxA9 is associated with development of myeloproliferative disorders and leukemia and indicates a poor prognosis. To investigate the molecular mechanisms by which HoxA9 promotes immortalization of hematopoietic cells, we generated growth factor dependent myeloid cells in which HoxA9 expression is regulated by administration of 4-hydroxy-tamoxifen. Maintenance of HoxA9 overexpression is required for continued cell survival and proliferation, even in the presence of growth factors. We show for the first time that maintenance of Bcl-2 expression is critical for HoxA9-dependent immortalization and influences the latency of HoxA9-dependent leukemia. Hematopoietic cells lacking Bcl-2 were not immortalized by HoxA9 in vitro. Furthermore, deletion of Bcl-2 delayed the onset and reduced the severity of HoxA9/Meis1 and MLL-AF9 leukemias. This is the first description of a molecular link between HoxA9 and the regulation of Bcl-2 family members in acute myeloid leukemia.
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Affiliation(s)
- Gabriela Brumatti
- Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Australia
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12
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Prosurvival Bcl-2 family members affect autophagy only indirectly, by inhibiting Bax and Bak. Proc Natl Acad Sci U S A 2014; 111:8512-7. [PMID: 24912196 DOI: 10.1073/pnas.1406425111] [Citation(s) in RCA: 158] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Antiapoptotic B-cell lymphoma 2 (Bcl-2) family members such as Bcl-2, myeloid cell leukemia 1 (Mcl-1), and B-cell lymphoma-X large (Bcl-xL) are proposed to inhibit autophagy by directly binding to the BH3 domain of Beclin 1/Atg6. However, these Bcl-2 family proteins also block the proapoptotic activity of Bcl-2-associated X (Bax) and Bcl-2 homologous antagonist/killer (Bak), and many inducers of autophagy also cause cell death. Therefore, when the mitochondrial-mediated apoptosis pathway is functional, interpretation of such experiments is complicated. To directly test the impact of the endogenous antiapoptotic Bcl-2 family members on autophagy in the absence of apoptosis, we inhibited their activity in cells lacking the essential cell death mediators Bax and Bak. We also used inducible lentiviral vectors to overexpress Bcl-2, Bcl-xL, or Mcl-1 in cells and subjected them to treatments that promote autophagy. In the absence of Bax and Bak, Bcl-2, Bcl-xL, and Mcl-1 had no detectable effect on autophagy or cell death in myeloid or fibroblast cell lines. On the other hand, when Bax and Bak were present, inhibiting the prosurvival Bcl-2 family members stimulated autophagy, but this correlated with increased cell death. In addition, inhibition of autophagy induced by amino acid starvation, etoposide, or interleukin-3 withdrawal did not affect cell death in the absence of Bax and Bak. These results demonstrate that the antiapoptotic Bcl-2 family members do not directly inhibit components of the autophagic pathway but instead affect autophagy indirectly, owing to their inhibition of Bax and Bak.
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13
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Wensveen FM, Geest CR, Libregts SFWM, Derks IAM, Ekert PG, Labi V, Villunger A, Nolte MA, Eldering E. BH3-only protein Noxa contributes to apoptotic control of stress-erythropoiesis. Apoptosis 2014; 18:1306-1318. [PMID: 23975731 PMCID: PMC3825139 DOI: 10.1007/s10495-013-0890-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Apoptosis plays an essential role in the control of erythropoiesis under normal and pathological conditions. However, the contribution of individual proteins within cell death signalling pathways remains poorly defined. Here, we investigated the role of the pro-apoptotic Bcl-2 family member Noxa in the regulation of erythropoiesis. We found that expression of Noxa is induced during erythroid differentiation of human and murine precursor cells. Using in vitro model systems for erythroid progenitors, we observed rapid induction of Noxa upon cytokine deprivation. Knockdown or deletion of Noxa conferred significant protection against apoptosis upon cytokine withdrawal. In vivo, Noxa deficiency did not affect hematological blood parameters or erythroid progenitor composition of bone marrow and spleen under steady-state conditions. In contrast, in a model of acute haemolytic anemia, Noxa-deficiency enhanced hematocrit recovery. Moreover, in a model of chronic inflammation-induced anemia, Noxa-ablation resulted in a dramatic increase of erythroblast expansion. Our data indicate that induction of Noxa in erythroid progenitors sets a survival threshold that limits expansion beyond the number of cells that can be sustained by the available cytokines, which becomes apparent under conditions of induced anemia.
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Affiliation(s)
- Felix M. Wensveen
- Department of Experimental Immunology, Academic Medical Center, Meibergdreef 8, 1105 AZ Amsterdam, The Netherlands
| | - Christian R. Geest
- Department of Experimental Immunology, Academic Medical Center, Meibergdreef 8, 1105 AZ Amsterdam, The Netherlands
| | - Sten F. W. M. Libregts
- Department of Experimental Immunology, Academic Medical Center, Meibergdreef 8, 1105 AZ Amsterdam, The Netherlands
| | - Ingrid A. M. Derks
- Department of Experimental Immunology, Academic Medical Center, Meibergdreef 8, 1105 AZ Amsterdam, The Netherlands
| | - Paul G. Ekert
- Division of Cell Signaling and Cell Death, The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Melbourne, VIC Australia
| | - Verena Labi
- Division of Developmental Immunology, BIOCENTER, Innsbruck Medical University, Innrain 80-82, 6020 Innsbruck, Austria
| | - Andreas Villunger
- Division of Developmental Immunology, BIOCENTER, Innsbruck Medical University, Innrain 80-82, 6020 Innsbruck, Austria
| | - Martijn A. Nolte
- Department of Experimental Immunology, Academic Medical Center, Meibergdreef 8, 1105 AZ Amsterdam, The Netherlands
- Department of Hematopoiesis, Sanquin Research and Landsteiner Laboratory AMC/UvA, Amsterdam, The Netherlands
| | - Eric Eldering
- Department of Experimental Immunology, Academic Medical Center, Meibergdreef 8, 1105 AZ Amsterdam, The Netherlands
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14
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Akhter R, Sanphui P, Biswas SC. The essential role of p53-up-regulated modulator of apoptosis (Puma) and its regulation by FoxO3a transcription factor in β-amyloid-induced neuron death. J Biol Chem 2014; 289:10812-10822. [PMID: 24567336 DOI: 10.1074/jbc.m113.519355] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Neurodegeneration underlies the pathology of Alzheimer disease (AD). The molecules responsible for such neurodegeneration in AD brain are mostly unknown. Recent findings indicate that the BH3-only proteins of the Bcl-2 family play an essential role in various cell death paradigms, including neurodegeneration. Here we report that Puma (p53-up-regulated modulator of apoptosis), an important member of the BH3-only protein family, is up-regulated in neurons upon toxic β-amyloid 1-42 (Aβ(1-42)) exposure both in vitro and in vivo. Down-regulation of Puma by specific siRNA provides significant protection against neuron death induced by Aβ(1-42). We further demonstrate that the activation of p53 and inhibition of PI3K/Akt pathways induce Puma. The transcription factor FoxO3a, which is activated when PI3K/Akt signaling is inhibited, directly binds with the Puma gene and induces its expression upon exposure of neurons to oligomeric Aβ(1-42). Moreover, Puma cooperates with another BH3-only protein, Bim, which is already implicated in AD. Our results thus suggest that Puma is activated by both p53 and PI3K/Akt/FoxO3a pathways and cooperates with Bim to induce neuron death in response to Aβ(1-42).
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Affiliation(s)
- Rumana Akhter
- Cell Biology and Physiology Division, Council of Scientific and Industrial Research (CSIR)-Indian Institute of Chemical Biology, 4 Raja S. C. Mullick Road, Kolkata 700 032, India
| | - Priyankar Sanphui
- Cell Biology and Physiology Division, Council of Scientific and Industrial Research (CSIR)-Indian Institute of Chemical Biology, 4 Raja S. C. Mullick Road, Kolkata 700 032, India
| | - Subhas Chandra Biswas
- Cell Biology and Physiology Division, Council of Scientific and Industrial Research (CSIR)-Indian Institute of Chemical Biology, 4 Raja S. C. Mullick Road, Kolkata 700 032, India.
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15
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Abstract
The role of apoptotic pathways in the development and function of the megakaryocyte lineage has generated renewed interest in recent years. This has been driven by the advent of BH3 mimetic drugs that target BCL2 family proteins to induce apoptosis in tumour cells: agents such as ABT-263 (navitoclax, which targets BCL2, BCL-XL [BCL2L1] and BCL2L2) and ABT-199 (a BCL2-specific agent) are showing great promise in early stage clinical trials. However, the major dose-limiting toxicity of navitoclax has proven to be thrombocytopenia, an on-target effect of inhibiting BCL-XL . It transpires that the anucleate platelet contains a classical intrinsic apoptosis pathway, which at steady state regulates its life span in the circulation. BCL-XL is the critical pro-survival protein that restrains apoptosis and maintains platelet viability. These findings have paved the way to a deeper understanding of apoptotic pathways and processes in platelets, and their precursor cell, the megakaryocyte.
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Affiliation(s)
- Benjamin T Kile
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Vic., Australia; Department of Medical Biology, The University of Melbourne, Parkville, Vic., Australia
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16
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Sandow JJ, Dorstyn L, O'Reilly LA, Tailler M, Kumar S, Strasser A, Ekert PG. ER stress does not cause upregulation and activation of caspase-2 to initiate apoptosis. Cell Death Differ 2013; 21:475-80. [PMID: 24292555 DOI: 10.1038/cdd.2013.168] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Revised: 10/13/2013] [Accepted: 10/29/2013] [Indexed: 01/14/2023] Open
Abstract
A recent report claimed that endoplasmic reticulum (ER) stress activates the ER trans-membrane receptor IRE1α, leading to increased caspase-2 levels via degradation of microRNAs, and consequently induction of apoptosis. This observation casts caspase-2 into a central role in the apoptosis triggered by ER stress. We have used multiple cell types from caspase-2-deficient mice to test this hypothesis but failed to find significant impact of loss of caspase-2 on ER-stress-induced apoptosis. Moreover, we did not observe increased expression of caspase-2 protein in response to ER stress. Our data strongly argue against a critical role for caspase-2 in ER-stress-induced apoptosis.
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Affiliation(s)
- J J Sandow
- 1] The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia [2] Department of Medical Biology, The University of Melbourne, Parkville, VIC 3052, Australia
| | - L Dorstyn
- 1] The Centre for Cancer Biology, SA Pathology, Adelaide, SA 5000, Australia [2] Department of Medicine, University of Adelaide, Adelaide, SA 5005, Australia [3] Division of Health Sciences, University of South Australia, Adelaide, SA 5001, Australia
| | - L A O'Reilly
- 1] The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia [2] Department of Medical Biology, The University of Melbourne, Parkville, VIC 3052, Australia
| | - M Tailler
- 1] The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia [2] Department of Medical Biology, The University of Melbourne, Parkville, VIC 3052, Australia
| | - S Kumar
- 1] The Centre for Cancer Biology, SA Pathology, Adelaide, SA 5000, Australia [2] Department of Medicine, University of Adelaide, Adelaide, SA 5005, Australia [3] Division of Health Sciences, University of South Australia, Adelaide, SA 5001, Australia
| | - A Strasser
- 1] The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia [2] Department of Medical Biology, The University of Melbourne, Parkville, VIC 3052, Australia
| | - P G Ekert
- 1] The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia [2] Department of Medical Biology, The University of Melbourne, Parkville, VIC 3052, Australia
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17
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Dai H, Pang YP, Ramirez-Alvarado M, Kaufmann SH. Evaluation of the BH3-only protein Puma as a direct Bak activator. J Biol Chem 2013; 289:89-99. [PMID: 24265320 DOI: 10.1074/jbc.m113.505701] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Interactions among Bcl-2 family proteins play critical roles in cellular life and death decisions. Previous studies have established the BH3-only proteins Bim, tBid, and Noxa as "direct activators" that are able to directly initiate the oligomerization and activation of Bak and/or Bax. Earlier studies of Puma have yielded equivocal results, with some concluding that it also acts as a direct activator and other studies suggesting that it acts solely as a sensitizer BH3-only protein. In the present study we examined the interaction of Puma BH3 domain or full-length protein with Bak by surface plasmon resonance, assessed Bak oligomerization status by cross-linking followed by immunoblotting, evaluated the ability of the Puma BH3 domain to induce Bak-mediated permeabilization of liposomes and mitochondria, and determined the effect of wild type and mutant Puma on cell viability in a variety of cellular contexts. Results of this analysis demonstrate high affinity (KD = 26 ± 5 nM) binding of the Puma BH3 domain to purified Bak ex vivo, leading to Bak homo-oligomerization and membrane permeabilization. Mutations in Puma that inhibit (L141E/M144E/L148E) or enhance (M144I/A145G) Puma BH3 binding to Bak also produce corresponding alterations in Bak oligomerization, Bak-mediated membrane permeabilization and, in a cellular context, Bak-mediated killing. Collectively, these results provide strong evidence that Puma, like Bim, Noxa, and tBid, is able to act as a direct Bak activator.
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18
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Ma WJ, Zhou Y, Shrestha A, Mao H, Li FY, Cheng NS, Zhang W, Xu RH, Zhang YQ, Jiang T, Feng H, Li W, Han Q. Applying chemical bile duct embolization to achieve chemical hepatectomy in hepatolithiasis: a further experimental study. J Surg Res 2013; 187:113-21. [PMID: 24290428 DOI: 10.1016/j.jss.2013.10.053] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Revised: 10/23/2013] [Accepted: 10/25/2013] [Indexed: 02/05/2023]
Abstract
BACKGROUND Hepatolithiasis is the presence of calculi within the bile ducts of the liver. It represents a significant problem for hepatobiliary surgery because of its high recurrence rate and the associated risk for partial hepatectomy. This study was designed to explore the long-term efficacy of chemical biliary duct embolization (CBDE) to treat recurrent hepatolithiasis. MATERIALS AND METHODS A rabbit model of hepatolithiasis was established, and CBDE was achieved using oxybenzene and N-butyl-cyanoacrylate. The short-term (6 wk) and long-term (12 wk) efficacy of CBDE treatment was compared by observing the degree of atrophy, fibrosis, proliferation of collagen fibers, and apoptosis of hepatocytes and hepatic stellate cells in the embolized hepatic lobe. Biochemical measurement of β-glucuronidase was also evaluated to determine the effect of CBDE on stone formation. RESULTS Six weeks after CBDE, there was liver cell destruction, collagen accumulation, and bile duct proliferation only in the peripheral part of the target lobe. Twelve weeks after CBDE, "self-cut" chemical hepatectomy was achieved, as manifested by the destruction of almost all the hepatocytes in the target lobe, bile duct proliferation, and collagen fiber accumulation. The β-glucuronidase activity was markedly lower in the embolized lobe than in the nonembolized lobe. In contrast, bax, caspase-3, caspase-9, and α-smooth muscle actin expression was substantially higher in the embolized lobe than in the sham-operation group at 6 wk, but was lower at 12 wk. CONCLUSIONS CBDE is a potentially effective therapeutic approach for treating and preventing the recurrence of hepatolithiasis.
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Affiliation(s)
- Wen-jie Ma
- Department of Hepatobiliary Surgery, West China Hospital of Sichuan University, Chengdu, China
| | - Yong Zhou
- Department of Hepatobiliary Surgery, West China Hospital of Sichuan University, Chengdu, China
| | - Anuj Shrestha
- Department of Hepatobiliary Surgery, West China Hospital of Sichuan University, Chengdu, China
| | - Hui Mao
- Department of Medicine, West China Hospital of Sichuan University, Chengdu, China.
| | - Fu-yu Li
- Department of Hepatobiliary Surgery, West China Hospital of Sichuan University, Chengdu, China.
| | - Nan-sheng Cheng
- Department of Hepatobiliary Surgery, West China Hospital of Sichuan University, Chengdu, China
| | - Wei Zhang
- Department of Medicine, The George Washington University, Washington, District of Columbia
| | - Rui-hua Xu
- Department of Hepatobiliary Surgery, West China Hospital of Sichuan University, Chengdu, China
| | - Yong-qiong Zhang
- Department of Hepatobiliary Surgery, West China Hospital of Sichuan University, Chengdu, China
| | - Ting Jiang
- Department of Hepatobiliary Surgery, West China Hospital of Sichuan University, Chengdu, China
| | - Huan Feng
- Department of Hepatobiliary Surgery, West China Hospital of Sichuan University, Chengdu, China
| | - Wen Li
- Department of Hepatobiliary Surgery, West China Hospital of Sichuan University, Chengdu, China
| | - Qiang Han
- Department of Hepatobiliary Surgery, West China Hospital of Sichuan University, Chengdu, China
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19
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Salmanidis M, Brumatti G, Narayan N, Green BD, van den Bergen JA, Sandow JJ, Bert AG, Silke N, Sladic R, Puthalakath H, Rohrbeck L, Okamoto T, Bouillet P, Herold MJ, Goodall GJ, Jabbour AM, Ekert PG. Hoxb8 regulates expression of microRNAs to control cell death and differentiation. Cell Death Differ 2013; 20:1370-80. [PMID: 23872792 DOI: 10.1038/cdd.2013.92] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Revised: 05/23/2013] [Accepted: 06/12/2013] [Indexed: 12/11/2022] Open
Abstract
Hoxb8 overexpression immortalises haematopoietic progenitor cells in a growth-factor-dependant manner and co-operates with interleukin-3 (IL-3) to cause acute myeloid leukaemia. To further understand how Hoxb8 contributes to myeloid cell immortalisation, we generated IL-3-dependant myeloid cells expressing Hoxb8 under the control of an inducible promoter. Downregulation of Hoxb8, in the presence of IL-3, caused cell-cycle arrest and apoptosis in the majority of cells. Apoptosis was dependant on Bax and Bak and, in part, on Bim, which was repressed by Hoxb8. Deletion of the miR-17∼92 seed sequences in the Bim 3'UTR abolished Hoxb8-dependant regulation of Bim reporter constructs. Expression of all six miRNAs from this cluster were elevated when Hoxb8 was overexpressed. The miR-17∼92 cluster was required for repression of Bim in Hoxb8-immortalised cells and deletion of the miR-17∼92 cluster substantially inhibited Hoxb8, but not Hoxa9, mediated survival and proliferation. Hoxb8 appears to promote miR-17∼92 expression through c-Myc, a known transcriptional regulator of the miR-17∼92 cluster. We have uncovered a previously unrecognised link between Hoxb8 expression and microRNAs that provides a new insight into the oncogenic functions of Hoxb8.
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Affiliation(s)
- M Salmanidis
- Cell signalling and Cell Death Division, Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria 3052, Australia
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20
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Akt1 is the principal Akt isoform regulating apoptosis in limiting cytokine concentrations. Cell Death Differ 2013; 20:1341-9. [PMID: 23787999 DOI: 10.1038/cdd.2013.63] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Revised: 04/29/2013] [Accepted: 05/14/2013] [Indexed: 11/08/2022] Open
Abstract
The activation of the Akt signalling in response to cytokine receptor signalling promotes protein synthesis, cellular growth and proliferation. To determine the role of Akt in interleukin-3 (IL-3) signalling, we generated IL-3-dependent myeloid cell lines from mice lacking Akt1, Akt2 or Akt3. Akt1 deletion resulted in accelerated apoptosis at low concentrations of IL-3. Expression of constitutively active Akt1 was sufficient to delay apoptosis in response to IL-3 withdrawal, but not sufficient to induce proliferation in the absence of IL-3. Akt1 prolonged survival of Bim- or Bad-deficient cells, but not cells lacking Puma, indicating that Akt1-dependent repression of apoptosis was in part dependent on Puma and independent of Bim or Bad. Our data show that a key role of Akt1 during IL-3 signalling is to repress p53-dependent apoptosis pathways, including transcriptional upregulation of Puma. Moreover, our data indicate that regulation of BH3-only proteins by Akt is dispensable for Akt-dependent cell survival.
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21
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Gurzeler U, Rabachini T, Dahinden CA, Salmanidis M, Brumatti G, Ekert PG, Echeverry N, Bachmann D, Simon HU, Kaufmann T. In vitro differentiation of near-unlimited numbers of functional mouse basophils using conditional Hoxb8. Allergy 2013; 68:604-13. [PMID: 23590216 DOI: 10.1111/all.12140] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/30/2013] [Indexed: 01/28/2023]
Abstract
BACKGROUND Basophils constitute a rare leukocyte population known for their effector functions in inflammation and allergy, as well as more recently described immunoregulatory roles. Besides their low frequency, functional analysis of basophils is hindered by a short life span, inefficient ex vivo differentiation protocols, and lack of suitable cell models. A method to produce large quantities of basophils in vitro would facilitate basophil research and constitute a sought-after tool for diagnostic and drug testing purposes. METHODS A method is described to massively expand bone marrow-derived basophils in vitro. Myeloid progenitors are conditionally immortalized using Hoxb8 in the presence of interleukin-3 (IL-3) and outgrowing cell lines selected for their potential to differentiate into basophils upon shutdown of Hoxb8 expression. RESULTS IL-3-dependent, conditional Hoxb8-immortalized progenitor cell lines can be expanded and maintained in culture for prolonged periods. Upon shutdown of Hoxb8 expression, near-unlimited numbers of mature functional basophils can be differentiated in vitro within six days. The cells are end-differentiated and short-lived and express basophil-specific surface markers and proteases. Upon IgE- as well as C5a-mediated activation, differentiated basophils release granule enzymes and histamine and secrete Th2-type cytokines (IL-4, IL-13) and leukotriene C4. IL-3-deprivation induces apoptosis correlating with upregulation of the BH3-only proteins BCL-2-interacting mediator of cell death (BIM) and p53 upregulated modulator of apoptosis (PUMA) and downregulation of proviral integration site for Moloney murine leukemia virus 1 kinase (PIM-1). CONCLUSION A novel method is presented to generate quantitative amounts of mouse basophils in vitro, which moreover allows genetic manipulation of conditionally immortalized progenitors. This approach may represent a useful alternative method to isolating primary basophils.
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Affiliation(s)
- U. Gurzeler
- Institute of Pharmacology; University of Bern; Bern; Switzerland
| | - T. Rabachini
- Institute of Pharmacology; University of Bern; Bern; Switzerland
| | - C. A. Dahinden
- Institute of Immunology; University of Bern; Bern; Switzerland
| | - M. Salmanidis
- The Walter and Eliza Hall Institute of Medical Research; Melbourne; Australia
| | - G. Brumatti
- The Walter and Eliza Hall Institute of Medical Research; Melbourne; Australia
| | - P. G. Ekert
- The Walter and Eliza Hall Institute of Medical Research; Melbourne; Australia
| | - N. Echeverry
- Institute of Pharmacology; University of Bern; Bern; Switzerland
| | - D. Bachmann
- Institute of Pharmacology; University of Bern; Bern; Switzerland
| | - H. U. Simon
- Institute of Pharmacology; University of Bern; Bern; Switzerland
| | - T. Kaufmann
- Institute of Pharmacology; University of Bern; Bern; Switzerland
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22
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Doan PL, Himburg HA, Helms K, Russell JL, Fixsen E, Quarmyne M, Harris JR, Deoliviera D, Sullivan JM, Chao NJ, Kirsch DG, Chute JP. Epidermal growth factor regulates hematopoietic regeneration after radiation injury. Nat Med 2013; 19:295-304. [PMID: 23377280 PMCID: PMC3594347 DOI: 10.1038/nm.3070] [Citation(s) in RCA: 134] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2012] [Accepted: 12/13/2012] [Indexed: 01/20/2023]
Abstract
The mechanisms which regulate HSC regeneration following myelosuppressive injury are not well understood. We identified epidermal growth factor (EGF) to be highly enriched in the bone marrow (BM) serum of mice bearing deletion of Bak and Bax in Tie2+ cells (Tie2Cre;Bak1−/−;Baxfl/− mice), which displayed radioprotection of the HSC pool and 100% survival following lethal dose total body irradiation (TBI). BM HSCs from wild type mice expressed functional EGFR and systemic administration of EGF promoted the recovery of the HSC pool in vivo and the improved survival of mice following TBI. Conversely, administration of erlotinib, an EGFR antagonist, significantly decreased both HSC regeneration and mice survival following TBI. VavCre;EGFRfl/+ mice also demonstrated delayed recovery of BM stem/progenitor cells following TBI compared to VavCre;EGFR+/+ mice. Mechanistically, EGF reduced radiation-induced apoptosis of HSCs and mediated this effect via repression of the proapoptotic protein, PUMA. EGFR signaling regulates HSC regeneration following myelosuppressive injury.
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Affiliation(s)
- Phuong L Doan
- Department of Medicine, Division of Hematologic Malignancies and Cellular Therapy, Durham, North Carolina, USA
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23
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Abstract
The PI3K pathway plays an important role in key cellular functions such as cell growth, proliferation and survival. Genetic and epigenetic alterations in different pathway components lead to aberrant pathway activation and have been observed in high frequencies in various tumor types. Consequently, significant effort has been made to develop antineoplastic agents targeting different nodes in this pathway. Additionally, PI3K pathway status may have predictive and prognostic implications, and may contribute to drug resistance in tumor cells. This article provides an overview of our current knowledge of the PI3K pathway with an emphasis on its application in cancer treatment.
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Affiliation(s)
- Navid Sadeghi
- Division of Hematology & Oncology, Harold C Simmons Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - David E Gerber
- Division of Hematology & Oncology, Harold C Simmons Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX, USA
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24
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Hercus TR, Broughton SE, Ekert PG, Ramshaw HS, Perugini M, Grimbaldeston M, Woodcock JM, Thomas D, Pitson S, Hughes T, D'Andrea RJ, Parker MW, Lopez AF. The GM-CSF receptor family: mechanism of activation and implications for disease. Growth Factors 2012; 30:63-75. [PMID: 22257375 DOI: 10.3109/08977194.2011.649919] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a pluripotent cytokine produced by many cells in the body, which regulates normal and malignant hemopoiesis as well as innate and adaptive immunity. GM-CSF assembles and activates its heterodimeric receptor complex on the surface of myeloid cells, initiating multiple signaling pathways that control key functions such as cell survival, cell proliferation, and functional activation. Understanding the molecular composition of these pathways, the interaction of the various components as well as the kinetics and dose-dependent mechanics of receptor activation provides valuable insights into the function of GM-CSF as well as the related cytokines, interleukin-3 and interleukin-5. This knowledge provides opportunities for the development of new therapies to block the action of these cytokines in hematological malignancy and chronic inflammation.
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Affiliation(s)
- Timothy R Hercus
- Centre for Cancer Biology, SA Pathology, Adelaide, South Australia, Australia
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25
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Jabbour AM, Gordon L, Daunt CP, Green BD, Kok CH, D'Andrea R, Ekert PG. p53-Dependent transcriptional responses to interleukin-3 signaling. PLoS One 2012; 7:e31428. [PMID: 22348085 PMCID: PMC3279357 DOI: 10.1371/journal.pone.0031428] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2011] [Accepted: 01/08/2012] [Indexed: 12/28/2022] Open
Abstract
p53 is critical in the normal response to a variety of cellular stresses including DNA damage and loss of p53 function is a common feature of many cancers. In hematological malignancies, p53 deletion is less common than in solid malignancies but is associated with poor prognosis and resistance to chemotherapy. Compared to their wild-type (WT) counterparts, hematopoietic progenitor cells lacking p53 have a greater propensity to survive cytokine loss, in part, due to the failure to transcribe Puma, a proapoptotic Bcl-2 family member. Using expression arrays, we have further characterized the differences that distinguish p53−/− cells from WT myeloid cells in the presence of Interleukin-3 (IL-3) to determine if such differences contribute to the increased clonogenicity and survival responses observed in p53−/− cells. We show that p53−/− cells have a deregulated intracellular signaling environment and display a more rapid and sustained response to IL-3. This was accompanied by an increase in active ERK1/2 and a dependence on an intact MAP kinase signaling pathway. Contrastingly, we find that p53−/− cells are independent on AKT for their survival. Thus, loss of p53 in myeloid cells results in an altered transcriptional and kinase signaling environment that favors enhanced cytokine signaling.
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Affiliation(s)
- Anissa M. Jabbour
- Children's Cancer Centre, Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia
- Cell Signalling and Cell Death, Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
- Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Parkville, Victoria, Australia
- * E-mail: (AMJ); (PGE)
| | - Lavinia Gordon
- Bioinformatics Unit, Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia
| | - Carmel P. Daunt
- Children's Cancer Centre, Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia
- Cell Signalling and Cell Death, Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
| | - Benjamin D. Green
- Children's Cancer Centre, Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia
- Cell Signalling and Cell Death, Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
- Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Parkville, Victoria, Australia
| | - Chung H. Kok
- Acute Leukaemia Laboratory and Department of Haematology, SA Pathology, Department of Haematology and Oncology, The Queen Elizabeth Hospital, Centre for Stem Cell Research, the University of Adelaide, Adelaide, South Australia, Australia
| | - Richard D'Andrea
- Acute Leukaemia Laboratory and Department of Haematology, SA Pathology, Department of Haematology and Oncology, The Queen Elizabeth Hospital, Centre for Stem Cell Research, the University of Adelaide, Adelaide, South Australia, Australia
| | - Paul G. Ekert
- Children's Cancer Centre, Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia
- Cell Signalling and Cell Death, Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
- Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Parkville, Victoria, Australia
- * E-mail: (AMJ); (PGE)
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26
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Vogel S, Raulf N, Bregenhorn S, Biniossek ML, Maurer U, Czabotar P, Borner C. Cytosolic Bax: does it require binding proteins to keep its pro-apoptotic activity in check? J Biol Chem 2012; 287:9112-27. [PMID: 22277657 DOI: 10.1074/jbc.m111.248906] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Bax is kept inactive in the cytosol by refolding its C-terminal transmembrane domain into the hydrophobic binding pocket. Although energetic calculations predicted this conformation to be stable, numerous Bax binding proteins were reported and suggested to further stabilize inactive Bax. Unfortunately, most of them have not been validated in a physiological context on the endogenous level. Here we use gel filtration analysis of the cytosol of primary and established cells to show that endogenous, inactive Bax runs 20-30 kDa higher than recombinant Bax, suggesting Bax dimerization or the binding of a small protein. Dimerization was excluded by a lack of interaction of differentially tagged Bax proteins and by comparing the sizes of dimerized recombinant Bax with cytosolic Bax on blue native gels. Surprisingly, when analyzing cytosolic Bax complexes by high sensitivity mass spectrometry after anti-Bax immunoprecipitation or consecutive purification by gel filtration and blue native gel electrophoresis, we detected only one protein, called p23 hsp90 co-chaperone, which consistently and specifically co-purified with Bax. However, this protein could not be validated as a crucial inhibitory Bax binding partner as its over- or underexpression did not show any apoptosis defects. By contrast, cytosolic Bax exhibits a slight molecular mass shift on SDS-PAGE as compared with recombinant Bax, which suggests a posttranslational modification and/or a structural difference between the two proteins. We propose that in most healthy cells, cytosolic endogenous Bax is a monomeric protein that does not necessarily need a binding partner to keep its pro-apoptotic activity in check.
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Affiliation(s)
- Sandra Vogel
- Institute of Molecular Medicine and Cell Research, Center for Biochemistry and Molecular Cell Research, Albert Ludwigs University, Freiburg, Germany
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27
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Cytokine receptor signaling activates an IKK-dependent phosphorylation of PUMA to prevent cell death. Cell Death Differ 2011; 19:633-41. [PMID: 21997190 DOI: 10.1038/cdd.2011.131] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
P53-upregulated modifier of apoptosis (PUMA), a pro-apoptotic member of the Bcl-2 family, is transcriptionally activated by p53 and is a key effector of p53-dependent apoptosis. We show that PUMA protein is subject to rapid post-translational regulation by phosphorylation at a conserved residue, serine 10, following serum or interleukin-3 (IL-3) stimulation. Serine 10 is not within the Bcl-2 homology (BH3) domain, and PUMA phosphorylated at serine 10 retained the ability to co-immunoprecipitate with antiapoptotic Bcl-2 family members. However, phosphorylated PUMA was targeted for proteasomal degradation indicating that it is less stable than unphosphorylated PUMA. Importantly, we identified IKK1/IKK2/Nemo as the kinase complex that interacts with and phosphorylates PUMA, thereby also demonstrating that IL-3 activates NFκB signaling. The identification and characterization of this novel survival pathway has important implications for IL-3 signaling and hematopoietic cell development.
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28
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Wensveen FM, Alves NL, Derks IAM, Reedquist KA, Eldering E. Apoptosis induced by overall metabolic stress converges on the Bcl-2 family proteins Noxa and Mcl-1. Apoptosis 2011; 16:708-21. [PMID: 21516346 PMCID: PMC3098366 DOI: 10.1007/s10495-011-0599-8] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
Apoptosis provoked by glucose shortage in dividing T cells is mediated via the BH3-only protein Noxa and inhibition of its binding partner Mcl-1. It is unknown how signals from cellular metabolism can affect the balance between Mcl-1 and Noxa and to what extent other Bcl-2 members are involved in this apoptosis cascade. Here, we defined the mechanism underlying apoptosis in relation to various types of metabolic stress. First, we established that the Noxa/Mcl-1 balance is regulated by glucose deprivation as well as by general metabolic stress, via changes in proteasome-mediated degradation of Mcl-1. Second, in contrast with cytokine-deprivation, no transcriptional modulation of Mcl-1, Puma, Bim or Noxa was observed during glucose deprivation. Third, no changes in PKB or GSK3 activity occurred and no clear role for AMPK was detected. Fourth, apoptosis triggered by nutrient deprivation was executed without signs of overt autophagy and independent of ROS production or p38 MAP kinase activity. Lastly, apoptosis under nutrient limitation could also be delayed by knock-down of Bim or overexpression of Bcl-2. In conclusion, Noxa functions in a specific apoptotic pathway that integrates overall nutrient stress, independent from attenuated PI3K/PKB signaling and without clear involvement of autophagy.
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Affiliation(s)
- Felix M. Wensveen
- Department of Experimental Immunology, Academic Medical Center, Meibergdreef 9, Room K0-144, 1105 AZ Amsterdam, The Netherlands
| | - Nuno L. Alves
- Department of Experimental Immunology, Academic Medical Center, Meibergdreef 9, Room K0-144, 1105 AZ Amsterdam, The Netherlands
- Present Address: Cell Activation and Gene Expression Group, Instituto de Biologia Molecular e Celular, Porto, Portugal
| | - Ingrid A. M. Derks
- Department of Experimental Immunology, Academic Medical Center, Meibergdreef 9, Room K0-144, 1105 AZ Amsterdam, The Netherlands
| | - Kris A. Reedquist
- Department of Clinical Immunology and Rheumatology, Academic Medical Center, Amsterdam, The Netherlands
| | - Eric Eldering
- Department of Experimental Immunology, Academic Medical Center, Meibergdreef 9, Room K0-144, 1105 AZ Amsterdam, The Netherlands
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29
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Rackham O, Shearwood AMJ, Thyer R, McNamara E, Davies SMK, Callus BA, Miranda-Vizuete A, Berners-Price SJ, Cheng Q, Arnér ESJ, Filipovska A. Substrate and inhibitor specificities differ between human cytosolic and mitochondrial thioredoxin reductases: Implications for development of specific inhibitors. Free Radic Biol Med 2011; 50:689-99. [PMID: 21172426 DOI: 10.1016/j.freeradbiomed.2010.12.015] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2010] [Revised: 12/09/2010] [Accepted: 12/10/2010] [Indexed: 10/18/2022]
Abstract
The cytosolic and mitochondrial thioredoxin reductases (TrxR1 and TrxR2) and thioredoxins (Trx1 and Trx2) are key components of the mammalian thioredoxin system, which is important for antioxidant defense and redox regulation of cell function. TrxR1 and TrxR2 are selenoproteins generally considered to have comparable properties, but to be functionally separated by their different compartments. To compare their properties we expressed recombinant human TrxR1 and TrxR2 and determined their substrate specificities and inhibition by metal compounds. TrxR2 preferred its endogenous substrate Trx2 over Trx1, whereas TrxR1 efficiently reduced both Trx1 and Trx2. TrxR2 displayed strikingly lower activity with dithionitrobenzoic acid (DTNB), lipoamide, and the quinone substrate juglone compared to TrxR1, and TrxR2 could not reduce lipoic acid. However, Sec-deficient two-amino-acid-truncated TrxR2 was almost as efficient as full-length TrxR2 in the reduction of DTNB. We found that the gold(I) compound auranofin efficiently inhibited both full-length TrxR1 and TrxR2 and truncated TrxR2. In contrast, some newly synthesized gold(I) compounds and cisplatin inhibited only full-length TrxR1 or TrxR2 and not truncated TrxR2. Surprisingly, one gold(I) compound, [Au(d2pype)(2)]Cl, was a better inhibitor of TrxR1, whereas another, [(iPr(2)Im)(2)Au]Cl, mainly inhibited TrxR2. These compounds also inhibited TrxR activity in the cytoplasm and mitochondria of cells, but their cytotoxicity was not always dependent on the proapoptotic proteins Bax and Bak. In conclusion, this study reveals significant differences between human TrxR1 and TrxR2 in substrate specificity and metal compound inhibition in vitro and in cells, which may be exploited for development of specific TrxR1- or TrxR2-targeting drugs.
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Affiliation(s)
- Oliver Rackham
- Western Australian Institute for Medical Research, Centre for Medical Research, University of Western Australia, Perth, WA 6000, Australia
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30
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Shao L, Goronzy JJ, Weyand CM. DNA-dependent protein kinase catalytic subunit mediates T-cell loss in rheumatoid arthritis. EMBO Mol Med 2011; 2:415-27. [PMID: 20878914 PMCID: PMC3017722 DOI: 10.1002/emmm.201000096] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
In the autoimmune syndrome rheumatoid arthritis (RA), T cells and T-cell precursors have age-inappropriate shortening of telomeres and accumulate deoxyribonucleic acid (DNA) double strand breaks. Whether damaged DNA elicits DNA repair activity and how this affects T-cell function and survival is unknown. Here, we report that naïve and resting T cells from RA patients are susceptible to undergo apoptosis. In such T cells, unrepaired DNA stimulates a p53-ataxia telangiectasia mutated-independent pathway involving the non-homologous-end-joining protein DNA-protein kinase catalytic subunit (DNA-PKcs). Upregulation of DNA-PKcs transcription, protein expression and phosphorylation in RA T cells co-occurs with diminished expression of the Ku70/80 heterodimer, limiting DNA repair capacity. Inhibition of DNA-PKcs kinase activity or gene silencing of DNA-PKcs protects RA T cells from apoptosis. DNA-PKcs induces T-cell death by activating the JNK pathway and upregulating the apoptogenic BH3-only proteins Bim and Bmf. In essence, in RA, the DNA-PKcs-JNK-Bim/Bmf axis transmits genotoxic stress into shortened survival of naïve resting T cells, imposing chronic proliferative turnover of the immune system and premature immunosenescence. Therapeutic blockade of the DNA-PK-dependent cell-death machinery may rejuvenate the immune system in RA.
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Affiliation(s)
- Lan Shao
- Department of Medicine, Immunology and Rheumatology, Stanford University, Stanford, CA, USA
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31
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Han JW, Zhan XR, Li XY, Xia B, Wang YY, Zhang J, Li BX. Impaired PI3K/Akt signal pathway and hepatocellular injury in high-fat fed rats. World J Gastroenterol 2010; 16:6111-8. [PMID: 21182226 PMCID: PMC3012583 DOI: 10.3748/wjg.v16.i48.6111] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To determine whether mitochondrial dysfunction resulting from high-fat diet is related to impairment of the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt, also known as PKB) pathway.
METHODS: Rat models of nonalcoholic fatty liver were established by high-fat diet feeding. The expression of total and phosphorylated P13K and Akt proteins in hepatocytes was determined by Western blotting. Degree of fat accumulation in liver was measured by hepatic triglyceride. Mitochondrial number and size were determined using quantitative morphometric analysis under transmission electron microscope. The permeability of the outer mitochondrial membrane was assessed by determining the potential gradient across this membrane.
RESULTS: After Wistar rats were fed with high-fat diet for 16 wk, their hepatocytes displayed an accumulation of fat (103.1 ± 12.6 vs 421.5 ± 19.7, P < 0.01), deformed mitochondria (9.0% ± 4.3% vs 83.0% ± 10.9%, P < 0.05), and a reduction in the mitochondrial membrane potential (389.385% ± 18.612% vs 249.121% ± 13.526%, P < 0.05). In addition, the expression of the phosphorylated P13K and Akt proteins in hepatocytes was reduced, as was the expression of the anti-apoptotic protein Bcl-2, while expression of the pro-apoptotic protein caspase-3 was increased. When animals were treated with pharmacological inhibitors of P13K or Akt, instead of high-fat diet, a similar pattern of hepatocellular fat accumulation, mitochondrial impairment, and change in the levels of PI3K, Akt, Bcl-2 was observed.
CONCLUSION: High-fat diet appears to inhibit the PI3K/Akt signaling pathway, which may lead to hepatocellular injury through activation of the mitochondrial membrane pathway of apoptosis.
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32
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Kutuk O, Temel SG, Tolunay S, Basaga H. Aven blocks DNA damage-induced apoptosis by stabilising Bcl-xL. Eur J Cancer 2010; 46:2494-505. [PMID: 20619636 DOI: 10.1016/j.ejca.2010.06.011] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2010] [Revised: 06/01/2010] [Accepted: 06/07/2010] [Indexed: 10/19/2022]
Abstract
Induction of apoptosis by DNA-damaging agents involves the activation of mitochondrial apoptotic pathway. Aven has been identified as an antiapoptotic protein and has been shown to activate ATM in response to DNA damage. In this study, we demonstrated that enforced expression of Aven blocks UV-irradiation-, SN-38- or cisplatin-induced apoptosis upstream of mitochondria by stabilising Bcl-xL protein levels in breast cancer cells. Aven silencing by RNA interference markedly enhanced apoptotic response following treatment with DNA-damaging agents. Aven is complexed with Bcl-xL in untreated breast cancer cells and treatment with DNA-damaging agents led to decreased Aven/Bcl-xL interaction. Importantly, Bcl-xL was necessary for the prosurvival activity of Aven and depletion of Bcl-xL abrogated Aven-mediated protection against DNA damage-induced apoptosis. Analysis of breast cancer tissue microarrays revealed decreased Aven nuclear expression in breast cancer tissues compared with non-neoplastic breast tissues. In particular, we detected reduced nuclear expression of Aven in infiltrating ductal carcinoma and papillary carcinoma breast cancer subtypes compared with non-neoplastic breast tissues and infiltrating lobular breast cancer tissues. Our results suggest that Aven is an important mediator in DNA damage-induced apoptotic signalling in breast cancer cells and its nuclear expression is altered in breast cancer tissues, which may contribute to genomic instability in breast cancer tumours.
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Affiliation(s)
- Ozgur Kutuk
- Biological Sciences and Bioengineering Program, Faculty of Natural Sciences and Engineering, Sabanci University, Istanbul, Turkey
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33
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Lopez AF, Hercus TR, Ekert P, Littler DR, Guthridge M, Thomas D, Ramshaw HS, Stomski F, Perugini M, D'Andrea R, Grimbaldeston M, Parker MW. Molecular basis of cytokine receptor activation. IUBMB Life 2010; 62:509-18. [DOI: 10.1002/iub.350] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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34
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Brumatti G, Salmanidis M, Ekert PG. Crossing paths: interactions between the cell death machinery and growth factor survival signals. Cell Mol Life Sci 2010; 67:1619-30. [PMID: 20157838 PMCID: PMC11115775 DOI: 10.1007/s00018-010-0288-8] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2010] [Accepted: 01/20/2010] [Indexed: 01/08/2023]
Abstract
Cytokines and growth factors play a crucial role in the maintenance of haematopoietic homeostasis. They transduce signals that regulate the competing commitments of haematopoietic stem cells, quiescence or proliferation, retention of stem cell pluripotency or differentiation, and survival or demise. When the balance between these commitments and the requirements of the organisms is disturbed, particularly when it favours survival and proliferation, cancer may result. Cell death provoked by loss of growth factor signalling is regulated by the Bcl-2 family of apoptosis regulators, and thus survival messages transduced by growth factors must regulate the activity of these proteins. Many aspects of direct interactions between cytokine signalling and regulation of apoptosis remain elusive. In this review, we explore the mechanisms by which cytokines, in particular Interleukin-3 and granulocyte-macrophage colony-stimulating factor, promote cell survival and suppress apoptosis as models of how cytokine signalling and apoptotic pathways intersect.
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Affiliation(s)
- Gabriela Brumatti
- Children's Cancer Centre, Murdoch Children's Research Institute, Royal Children's Hospital, Department of Paediatrics, University of Melbourne, Flemington Rd Parkville, Melbourne, 3052, Australia.
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35
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Individual and overlapping roles of BH3-only proteins Bim and Bad in apoptosis of lymphocytes and platelets and in suppression of thymic lymphoma development. Cell Death Differ 2010; 17:1655-64. [PMID: 20431598 PMCID: PMC2953537 DOI: 10.1038/cdd.2010.43] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
BH3-only proteins, such as Bim and Bad, contribute to tissue homeostasis by initiating apoptosis in a cell type- and stimulus-specific manner. Loss of Bim provokes lymphocyte accumulation in vivo and renders lymphocytes more resistant to diverse apoptotic stimuli and Bad has been implicated in the apoptosis of haematopoietic cells upon cytokine deprivation. To investigate whether their biological roles in apoptosis overlap, we generated mice lacking both Bim and Bad and compared their haematopoietic phenotype with that of the single-knockout and wild-type (wt) animals. Unexpectedly, bad(-/-) mice had excess platelets due to prolonged platelet life-span. The bim(-/-)bad(-/-) mice were anatomically normal and fertile. Their haematopoietic phenotype resembled that of bim(-/-) mice but lymphocytes were slightly more elevated in their lymph nodes. Although resting B and T lymphocytes from bim(-/-)bad(-/-) and bim(-/-) animals displayed similar resistance to diverse apoptotic stimuli, mitogen activated bim(-/-)bad(-/-) B cells were more refractory to cytokine deprivation. Moreover, combined loss of Bim and Bad-enhanced survival of thymocytes after DNA damage and accelerated development of γ-irradiation-induced thymic lymphoma. Unexpectedly, their cooperation in the thymus depended upon thymocyte-stromal interaction. Collectively, these results show that Bim and Bad can cooperate in the apoptosis of thymocytes and activated B lymphocytes and in the suppression of thymic lymphoma development.
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36
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Lysosomal membrane permeabilization and cathepsin release is a Bax/Bak-dependent, amplifying event of apoptosis in fibroblasts and monocytes. Cell Death Differ 2010; 17:1167-78. [PMID: 20094062 DOI: 10.1038/cdd.2009.214] [Citation(s) in RCA: 135] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Apoptotic stimuli have been shown to trigger lysosomal membrane permeability (LMP), leading to the release of cathepsins, which activate death signaling pathways in the cytosol. However, it is unknown whether this process is an initiating or amplifying event in apoptosis. In this study, we used fibroblasts and monocytes exposed to etoposide, ultraviolet light, FasL or deprived of interleukin-3 (IL-3) to show that LMP and the cytosolic release of cathepsins B, L and D consistently depends on Bax/Bak and components of the apoptosome. Neither Bax nor Bak resided on the lysosomes, indicating that lysosomes were not directly perforated by Bax/Bak but by effectors downstream of the apoptosome. Detailed kinetic analysis of cells lacking cathepsin B or L or treated with the cysteine protease inhibitor, E64d, revealed a delay in these cells in etoposide- and IL-3 deprivation-induced caspase-3 activation and apoptosis induction but not clonogenic survival, indicating that cathepsins amplify rather than initiate apoptosis.
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37
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Myeloid progenitor cells lacking p53 exhibit delayed up-regulation of Puma and prolonged survival after cytokine deprivation. Blood 2009; 115:344-52. [PMID: 19965665 DOI: 10.1182/blood-2009-07-230730] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Loss of p53-dependent apoptosis contributes to the development of hematologic malignancies and failure to respond to treatment. Proapoptotic Bcl-2 family member Puma is essential for apoptosis in HoxB8-immortalized interleukin-3 (IL-3)-dependent myeloid cell lines (FDM cells) provoked by IL-3 deprivation. p53 and FoxO3a can transcriptionally regulate Puma. To investigate which transcriptional regulator is responsible for IL-3 deprivation-induced Puma expression and apoptosis, we generated wild-type (WT), p53(-/-), and FoxO3a(-/-) FDM cells and found that p53(-/-) but not FoxO3a(-/-) cells were protected against IL-3 withdrawal. Loss of p21(cip/waf), which is critical for p53-mediated cell-cycle arrest, afforded no protection against IL-3 deprivation. A survival advantage was also observed in untransformed p53(-/-) hematopoietic progenitor cells cultured in the presence or absence of cytokines. In response to IL-3 deprivation, increased Puma protein levels in p53(-/-) cells were substantially delayed compared with WT cells. Increased p53 transcriptional activity was detected after cytokine deprivation. This was substantially less than that induced by DNA damage and associated not with increased p53 protein levels but with loss of the p53 regulator, MDM2. Thus, we conclude that p53 protein is activated after IL-3 deprivation by loss of MDM2. Activated p53 transcriptionally up-regulates Puma, which initiates apoptosis.
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38
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Fortin SP, Ennis MJ, Savitch BA, Carpentieri D, McDonough WS, Winkles JA, Loftus JC, Kingsley C, Hostetter G, Tran NL. Tumor necrosis factor-like weak inducer of apoptosis stimulation of glioma cell survival is dependent on Akt2 function. Mol Cancer Res 2009; 7:1871-81. [PMID: 19861406 DOI: 10.1158/1541-7786.mcr-09-0194] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Malignant gliomas are the most common primary brain tumors. Despite intensive clinical investigation and significant technical advances in surgical and radiation treatment, the impact on clinical outcome for patients with malignant gliomas is disappointing. We have previously shown that tumor necrosis factor-like weak inducer of apoptosis (TWEAK), a member of the tumor necrosis factor superfamily, can stimulate glioma cell survival via binding to the Fn14 receptor, activation of the NF-kappaB pathway, and upregulation of BCL-X(L) gene expression. Here, we show that TWEAK treatment of glioma cells leads to phosphorylation of Akt and BAD. TWEAK stimulation results in the phosphorylation of both Akt1 and Akt2. However, small interfering RNA (siRNA)-mediated depletion of either Akt1 or Akt2 showed that BAD serine 136 phosphorylation is dependent specifically on Akt2 function. Depletion of Akt2 expression by siRNA also abrogates TWEAK-stimulated glioma cell survival, whereas no effect on glioma cell survival was observed after siRNA-mediated depletion of Akt1 expression. Surprisingly, although siRNA-mediated depletion of BAD in glioma cells abrogates cytotoxic- and chemotherapy-induced apoptosis, TWEAK still displays a strong protective effect, suggesting that BAD serine 136 phosphorylation plays a minor role in TWEAK-Akt2-induced glioma cell survival. We also report here that AKT2 gene expression levels increased with glioma grade and inversely correlate with patient survival. Additionally, immunohistochemical analysis showed that Akt2 expression positively correlates with Fn14 expression in glioblastoma multiforme specimens. We hypothesize that the TWEAK-Fn14 signaling axis functions, in part, to enhance glioblastoma cell survival by activation of the Akt2 serine/threonine protein kinase.
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Affiliation(s)
- Shannon P Fortin
- Cancer and Cell Biology Division, Translational Genomics Research Institute, Phoenix, AZ 85004, USA
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39
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Abstract
PUMA (p53 upregulated modulator of apoptosis) is a Bcl-2 homology 3 (BH3)-only Bcl-2 family member and a critical mediator of p53-dependent and -independent apoptosis induced by a wide variety of stimuli, including genotoxic stress, deregulated oncogene expression, toxins, altered redox status, growth factor/cytokine withdrawal and infection. It serves as a proximal signaling molecule whose expression is regulated by transcription factors in response to these stimuli. PUMA transduces death signals primarily to the mitochondria, where it acts indirectly on the Bcl-2 family members Bax and/or Bak by relieving the inhibition imposed by antiapoptotic members. It directly binds and antagonizes all known antiapoptotic Bcl-2 family members to induce mitochondrial dysfunction and caspase activation. PUMA ablation or inhibition leads to apoptosis deficiency underlying increased risks for cancer development and therapeutic resistance. Although elevated PUMA expression elicits profound chemo- and radiosensitization in cancer cells, inhibition of PUMA expression may be useful for curbing excessive cell death associated with tissue injury and degenerative diseases. Therefore, PUMA is a general sensor of cell death stimuli and a promising drug target for cancer therapy and tissue damage.
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Affiliation(s)
- J Yu
- Department of Pathology, University of Pittsburgh Cancer Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
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40
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The granulocyte-macrophage colony-stimulating factor receptor: linking its structure to cell signaling and its role in disease. Blood 2009; 114:1289-98. [PMID: 19436055 DOI: 10.1182/blood-2008-12-164004] [Citation(s) in RCA: 227] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Already 20 years have passed since the cloning of the granulocyte-macrophage colony-stimulating factor (GM-CSF) receptor alpha-chain, the first member of the GM-CSF/interleukin (IL)-3/IL-5 family of hemopoietic cytokine receptors to be molecularly characterized. The intervening 2 decades have uncovered a plethora of biologic functions transduced by the GM-CSF receptor (pleiotropy) and revealed distinct signaling networks that couple the receptor to biologic outcomes. Unlike other hemopoietin receptors, the GM-CSF receptor has a significant nonredundant role in myeloid hematologic malignancies, macrophage-mediated acute and chronic inflammation, pulmonary homeostasis, and allergic disease. The molecular mechanisms underlying GM-CSF receptor activation have recently been revealed by the crystal structure of the GM-CSF receptor complexed to GM-CSF, which shows an unexpected higher order assembly. Emerging evidence also suggests the existence of intracellular signosomes that are recruited in a concentration-dependent fashion to selectively control cell survival, proliferation, and differentiation by GM-CSF. These findings begin to unravel the mystery of cytokine receptor pleiotropy and are likely to also apply to the related IL-3 and IL-5 receptors as well as other heterodimeric cytokine receptors. The new insights in GM-CSF receptor activation have clinical significance as the structural and signaling nuances can be harnessed for the development of new treatments for malignant and inflammatory diseases.
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41
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Concurrent up-regulation of BCL-XL and BCL2A1 induces approximately 1000-fold resistance to ABT-737 in chronic lymphocytic leukemia. Blood 2009; 113:4403-13. [DOI: 10.1182/blood-2008-08-173310] [Citation(s) in RCA: 262] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Abstract
ABT-737 and its orally active analog, ABT-263, are rationally designed inhibitors of BCL2 and BCL-XL. ABT-263 shows promising activity in early phase 1 clinical trials in B-cell malignancies, particularly chronic lymphocytic leukemia (CLL). In vitro, peripheral blood CLL cells are extremely sensitive to ABT-737 (EC50 ∼7 nM), with rapid induction of apoptosis in all 60 patients tested, independent of parameters associated with disease progression and chemotherapy resistance. In contrast to data from cell lines, ABT-737–induced apoptosis in CLL cells was largely MCL1-independent. Because CLL cells within lymph nodes are more resistant to apoptosis than those in peripheral blood, CLL cells were cultured on CD154-expressing fibroblasts in the presence of interleukin-4 (IL-4) to mimic the lymph node microenvironment. CLL cells thus cultured developed an approximately 1000-fold resistance to ABT-737 within 24 hours. Investigations of the underlying mechanism revealed that this resistance occurred upstream of mitochondrial perturbation and involved de novo synthesis of the antiapoptotic proteins BCL-XL and BCL2A1, which were responsible for resistance to low and high ABT-737 concentrations, respectively. Our data indicate that after therapy with ABT-737–related inhibitors, resistant CLL cells might develop in lymph nodes in vivo and that treatment strategies targeting multiple BCL2 antiapoptotic members simultaneously may have synergistic activity.
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42
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Jabbour AM, Heraud JE, Daunt CP, Kaufmann T, Sandow J, O'Reilly LA, Callus BA, Lopez A, Strasser A, Vaux DL, Ekert PG. Puma indirectly activates Bax to cause apoptosis in the absence of Bid or Bim. Cell Death Differ 2008; 16:555-63. [PMID: 19079139 DOI: 10.1038/cdd.2008.179] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Bcl-2 family members regulate apoptosis in response to cytokine withdrawal and a broad range of cytotoxic stimuli. Pro-apoptotic Bcl-2 family members Bax and Bak are essential for apoptosis triggered by interleukin-3 (IL-3) withdrawal in myeloid cells. The BH3-only protein Puma is critical for initiation of IL-3 withdrawal-induced apoptosis, because IL-3-deprived Puma(-/-) cells show increased capacity to form colonies when IL-3 is restored. To investigate the mechanisms of Puma-induced apoptosis and the interactions between Puma and other Bcl-2 family members, we expressed Puma under an inducible promoter in cells lacking one or more Bcl-2 family members. Puma rapidly induced apoptosis in cells lacking the BH3-only proteins, Bid and Bim. Puma expression resulted in activation of Bax, but Puma killing was not dependent on Bax or Bak alone as Puma readily induced apoptosis in cells lacking either of these proteins, but could not kill cells deficient for both. Puma co-immunoprecipitated with the anti-apoptotic Bcl-2 family members Bcl-x(L) and Mcl-1 but not with Bax or Bak. These data indicate that Puma functions, in the context of induced overexpression or IL-3 deprivation, primarily by binding and inactivating anti-apoptotic Bcl-2 family members.
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Affiliation(s)
- A M Jabbour
- Children's Cancer Centre, Murdoch Children's Research Institute, Royal Children's Hospital, Flemington Road, Parkville, Victoria, Australia.
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Abstract
The activation of PI3K (phosphoinositide 3-kinase) family members is a universal event in response to virtually all cytokines, growth factors and hormones. As a result of formation of PtdIns with an added phosphate at the 3 position of the inositol ring, activation of the protein kinases PDK1 (phosphoinositide-dependent kinase 1) and PKB (protein kinase B)/Akt occurs. The PI3K/PKB pathway impinges upon a remarkable array of intracellular events that influence either directly or indirectly whether or not a cell will undergo apoptosis. In this review, the many ways in which PI3K/PKB can control these processes are summarized. Not all of the events described will necessarily play a role in any one cell type, but a subset of these events is probably essential for the survival of every cell.
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Callus BA, Moujallad DM, Silke J, Gerl R, Jabbour AM, Ekert PG, Vaux DL. Triggering of apoptosis by Puma is determined by the threshold set by prosurvival Bcl-2 family proteins. J Mol Biol 2008; 384:313-23. [PMID: 18835564 DOI: 10.1016/j.jmb.2008.09.041] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2008] [Revised: 09/12/2008] [Accepted: 09/15/2008] [Indexed: 10/21/2022]
Abstract
Puma (p53 upregulated modulator of apoptosis) belongs to the BH3 (Bcl-2 homology 3)-only protein family of apoptotic regulators. Its expression is induced by various apoptotic stimuli, including irradiation and cytokine withdrawal. Using an inducible system to express Puma, we investigated the nature of Puma-induced apoptosis. In BaF(3) cells, expression of Puma caused rapid caspase-mediated cleavage of ICAD (inhibitor of caspase-activated deoxyribonuclease) and Mcl-1 (myeloid cell leukemia 1), leading to complete loss of cell viability. Surprisingly, Puma protein levels peaked within 2 h of its induction and subsequently declined to basal levels. Maximal Puma abundance coincided with the onset of caspase activity. Subsequent loss of Puma was prevented by the inhibition of caspases, indicating that its degradation was caspase dependent. In cells expressing transfected Bcl-2, induced Puma reached significantly higher levels, but after a delay, caspases became active and cell death occurred. Puma co-immunoprecipitated endogenous Bcl-2 and Mcl-1 but not Bax and Bak, suggesting that Puma did not associate with either Bax or Bak in these cells to initiate cell death. In mouse embryonic fibroblasts (MEFs), the amount of Puma peaked within 4 h of its induction. In contrast, in bax/bak double-knockout MEFs, Puma was stably expressed following its induction and was unable to trigger apoptosis even at very high levels. Overexpression of Bcl-2 in wild-type MEFs, like in BaF(3) cells, resulted in higher levels of Puma being reached but did not prevent cell death from occurring. These results demonstrate that the level of the Bcl-2 prosurvival family sets the threshold at which Puma is able to indirectly activate Bax or Bak, leading in turn to activation of caspases that not only cause cell death but also rapidly induce Puma degradation.
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Affiliation(s)
- Bernard A Callus
- Department of Biochemistry, La Trobe University, Victoria 3086, Australia.
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45
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Abstract
The contribution of basophils in allergic disease and other Th2-type immune responses depends on their persistence at sites of inflammation, but the ligands and molecular pathways supporting basophil survival are largely unknown. The comparison of rates of apoptosis and of the expression of antiapoptotic proteins in different human granulocyte types revealed that basophils have a considerably longer spontaneous life span than neutrophils and eosinophils consistent with high levels of constitutive Bcl-2 expression. Interleukin-3 (IL-3) is the only ligand that efficiently protects basophils from apoptosis as evidenced by screening a large number of stimuli. IL-3 up-regulates the expression of the antiapoptotic proteins cIAP2, Mcl-1, and Bcl-X(L) and induces a rapid and sustained de novo expression of the serine/threonine kinase Pim1 that closely correlates with cytokine-enhanced survival. Inhibitor studies and protein transduction of primary basophils using wild-type and kinase-dead Pim1-Tat fusion-proteins demonstrate the functional importance of Pim1 induction in the IL-3-enhanced survival. Our data further indicate that the antiapoptotic Pim1-mediated pathway operates independently of PI3-kinase but involves the activation of p38 MAPK. The induction of Pim1 leading to PI3-kinase-independent survival as described here for basophils may also be a relevant antiapoptotic mechanism in other terminally differentiated leukocyte types.
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Ming L, Sakaida T, Yue W, Jha A, Zhang L, Yu J. Sp1 and p73 activate PUMA following serum starvation. Carcinogenesis 2008; 29:1878-84. [PMID: 18579560 DOI: 10.1093/carcin/bgn150] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
p53-upregulated modulator of apoptosis (PUMA) plays an essential role in p53-dependent apoptosis following DNA damage. PUMA also mediates apoptosis independent of p53. In this study, we investigated the role and mechanism of PUMA induction in response to serum starvation in p53-deficient cancer cells. Following serum starvation, the binding of Sp1 to the PUMA promoter significantly increased, whereas inhibition of Sp1 completely abrogated PUMA induction. p73 was found to be upregulated by serum starvation and mediate PUMA induction through the p53-binding sites in the PUMA promoter. Sp1 and p73beta appeared to cooperatively activate PUMA transcription, which is inhibited by the phosphoinsitide 3-kinase (PI3K)-protein kinase B (AKT) pathway. Furthermore, knockdown of PUMA suppressed serum starvation-induced apoptosis in leukemia cells. Our results suggest that transcription factors Sp1 and p73 mediate p53-independent induction of PUMA following serum starvation to trigger apoptosis in human cancer cells.
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Affiliation(s)
- Lihua Ming
- Department of Pathology, University of Pittsburgh Cancer Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
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47
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Apoptosis induced by Semliki Forest virus is RNA replication dependent and mediated via Bak. Cell Death Differ 2008; 15:1396-407. [PMID: 18437160 DOI: 10.1038/cdd.2008.61] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The RNA alphavirus Semliki Forest (SFV) triggers apoptosis in various mammalian cells, but it has remained controversial at what infection stage and by which signalling pathways host cells are killed. Both RNA synthesis-dependent and -independent initiation processes and mitochondrial as well as death receptor signalling pathways have been implicated. Here, we show that SFV-induced apoptosis is initiated at the level of RNA replication or thereafter. Moreover, by expressing antiapoptotic genes from recombinant SFV (replicons) and by using neutralizing reagents and gene-knockout cells, we provide clear evidence that SFV does not require CD95L-, TRAIL (tumor necrosis factor-related apoptosis-inducing ligand)- or tumor necrosis factor-mediated signalling but mitochondrial Bak to trigger cytochrome c release, the fall in the mitochondrial membrane potential, apoptotic protease-activating factor-1/caspase-9 apoptosome formation and caspase-3/-7 activation. Of seven BH3-only proteins tested, only Bid contributed to effective SFV-induced apoptosis. However, caspase-8 activation and Bid cleavage occurred downstream of Bax/Bak, indicating that truncated Bid formation serves to amplify rather than trigger SFV-induced apoptosis. Our data show that SFV sequentially activates a mitochondrial, Bak-mediated, caspase-8-dependent and Bid-mediated death signalling pathway that can be accurately dissected with gene-knockout cells and SFV replicons carrying antiapoptotic genes.
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Götschel F, Kern C, Lang S, Sparna T, Markmann C, Schwager J, McNelly S, von Weizsäcker F, Laufer S, Hecht A, Merfort I. Inhibition of GSK3 differentially modulates NF-kappaB, CREB, AP-1 and beta-catenin signaling in hepatocytes, but fails to promote TNF-alpha-induced apoptosis. Exp Cell Res 2007; 314:1351-66. [PMID: 18261723 DOI: 10.1016/j.yexcr.2007.12.015] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2007] [Revised: 12/14/2007] [Accepted: 12/19/2007] [Indexed: 01/29/2023]
Abstract
Glycogen synthase kinase-3 (GSK-3) is known to modulate cell survival and apoptosis through multiple intracellular signaling pathways. However, its hepatoprotective function and its role in activation of NF-kappaB and anti-apoptotic factors are poorly understood and remain controversial. Here we investigated whether inhibition of GSK-3 could induce apoptosis in the presence of TNF-alpha in primary mouse hepatocytes. We show that pharmacological inhibition of GSK-3 in primary mouse hepatocytes does not lead to TNF-alpha-induced apoptosis despite reduced NF-kappaB activity. Enhanced stability of IkappaB-alpha appears to be responsible for lower levels of nuclear NF-kappaB and hence reduced transactivation. Additionally, inhibition of GSK-3 was accompanied by marked upregulation of beta-catenin, AP-1, and CREB transcription factors. Stimulation of canonical Wnt signaling and CREB activity led to elevated levels of anti-apoptotic factors. Hence, survival of primary mouse hepatocytes may be caused by the activation and/or upregulation of other key regulators of liver homeostasis and regeneration. These signaling molecules may compensate for the compromised anti-apoptotic function of NF-kappaB and allow survival of hepatocytes in the presence of TNF-alpha and GSK-3 inhibition.
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Affiliation(s)
- Frank Götschel
- Institute of Molecular Medicine and Cell Research, University of Freiburg, Germany
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Callus BA, Ekert PG, Heraud JE, Jabbour AM, Kotevski A, Vince JE, Silke J, Vaux DL. Cytoplasmic p53 is not required for PUMA-induced apoptosis. Cell Death Differ 2007; 15:213-5; author reply 215-6. [PMID: 17992194 DOI: 10.1038/sj.cdd.4402245] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
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50
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Monomeric IgE and lipopolysaccharide synergistically prevent mast-cell apoptosis. Biochem Biophys Res Commun 2007; 365:137-42. [PMID: 17980154 DOI: 10.1016/j.bbrc.2007.10.136] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2007] [Accepted: 10/24/2007] [Indexed: 11/20/2022]
Abstract
The apoptosis of bone marrow-derived mast-cells (BMMCs) after growth factor withdrawal was significantly prevented by a high concentration of IgE in the absence of antigen, and further enhanced by the presence of Toll-like receptor4 (TLR4) ligand, lipopolysaccharide (LPS). The effect of LPS was mediated by TLR4, since TLR4-deficient BMMCs did not show synergistic effects with IgE. The neutralizing amount of anti-IL-3 did not reverse the anti-apoptotic effects of both IgE and combination with LPS. LPS treatment with monomeric IgE synergistically prevented the loss of mitochondrial membrane potentials and was associated with an enhanced expression of anti-apoptotic protein, Bcl-xL, or with a reduced expression of proapoptotic protein, Puma, and Bim, respectively. Altogether, these results suggest that LPS, in a TLR4-dependent manner, together with IgE, synergistically prevent mast-cell apoptosis and may contribute to regulate the tissue mast-cell number.
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