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Subcellular localization of X-linked inhibitor of apoptosis protein (XIAP) in cancer: does that matter? BBA ADVANCES 2022; 2:100050. [PMID: 37082602 PMCID: PMC10074912 DOI: 10.1016/j.bbadva.2022.100050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 02/25/2022] [Accepted: 03/15/2022] [Indexed: 11/20/2022] Open
Abstract
X-linked inhibitor of apoptosis protein (XIAP) finely tunes the balance between survival and death to control homeostasis. XIAP is found aberrantly expressed in cancer, which has been shown to promote resistance to therapy-induced apoptosis and confer poor outcome. Despite its predominant cytoplasmic localization in human tissues, growing evidence implicates the expression of XIAP in other subcellular compartments in sustaining cancer hallmarks. Herein, we review our current knowledge on the prognostic role of XIAP localization and discuss molecular mechanisms underlying differential biological functions played in each compartment. The comprehension of XIAP subcellular shuttling and functional dynamics might provide the rationale for future anticancer therapeutics.
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Delbue D, Mendonça BS, Robaina MC, Lemos LGT, Lucena PI, Viola JPB, Magalhães LM, Crocamo S, Oliveira CAB, Teixeira FR, Maia RC, Nestal de Moraes G. Expression of nuclear XIAP associates with cell growth and drug resistance and confers poor prognosis in breast cancer. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2020; 1867:118761. [PMID: 32485270 DOI: 10.1016/j.bbamcr.2020.118761] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Revised: 05/05/2020] [Accepted: 05/27/2020] [Indexed: 12/17/2022]
Abstract
Evasion from apoptosis is one of the hallmarks of cancer. X-linked inhibitor of apoptosis protein (XIAP) is known to modulate apoptosis by inhibiting caspases and ubiquitinating target proteins. XIAP is mainly found at the cytoplasm, but recent data link nuclear XIAP to poor prognosis in breast cancer. Here, we generated a mutant form of XIAP with a nuclear localization signal (XIAPNLS-C-term) and investigated the oncogenic mechanisms associated with nuclear XIAP in breast cancer. Our results show that cells overexpressing XIAPΔRING (RING deletion) and XIAPNLS-C-term exhibited XIAP nuclear localization more abundantly than XIAPwild-type. Remarkably, overexpression of XIAPNLS-C-term, but not XIAPΔRING, conferred resistance to doxorubicin and increased cellular proliferative capacity. Interestingly, Survivin and c-IAP1 expression were not associated with XIAP oncogenic effects. However, NFκB expression and ubiquitination of K63, but not K48 chains, were increased following XIAPNLS-C-term overexpression, pointing to nuclear signaling transduction. Consistently, multivariate analysis revealed nuclear, but not cytoplasmic XIAP, as an independent prognostic factor in hormone receptor-negative breast cancer patients. Altogether, our findings suggest that nuclear XIAP confers poor outcome and RING-associated breast cancer growth and chemoresistance.
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Affiliation(s)
- Deborah Delbue
- Laboratório de Hemato-Oncologia Celular e Molecular, Programa de Hemato-Oncologia Molecular, Instituto Nacional de Câncer (INCA), Praça da Cruz Vermelha, 23, 6° andar, Centro, 20 230 130 Rio de Janeiro, RJ, Brazil
| | - Bruna S Mendonça
- Laboratório de Hemato-Oncologia Celular e Molecular, Programa de Hemato-Oncologia Molecular, Instituto Nacional de Câncer (INCA), Praça da Cruz Vermelha, 23, 6° andar, Centro, 20 230 130 Rio de Janeiro, RJ, Brazil; Programa de Pós-Graduação Stricto Sensu em Oncologia, INCA, Rua André Cavalcanti, 37, 5° andar, Centro, 20 230 050, RJ, Brazil
| | - Marcela C Robaina
- Laboratório de Hemato-Oncologia Celular e Molecular, Programa de Hemato-Oncologia Molecular, Instituto Nacional de Câncer (INCA), Praça da Cruz Vermelha, 23, 6° andar, Centro, 20 230 130 Rio de Janeiro, RJ, Brazil
| | - Lauana G T Lemos
- Laboratório de Hemato-Oncologia Celular e Molecular, Programa de Hemato-Oncologia Molecular, Instituto Nacional de Câncer (INCA), Praça da Cruz Vermelha, 23, 6° andar, Centro, 20 230 130 Rio de Janeiro, RJ, Brazil
| | - Pedro I Lucena
- Programa de Imunologia e Biologia Tumoral, INCA, Rua André Cavalcanti, 37, 5° andar, Centro, 20 230 050, RJ, Brazil
| | - João P B Viola
- Programa de Imunologia e Biologia Tumoral, INCA, Rua André Cavalcanti, 37, 5° andar, Centro, 20 230 050, RJ, Brazil
| | - Lídia M Magalhães
- Divisão de Anatomia Patológica, INCA, Rua Cordeiro da Graça, 156, Santo Cristo, 20 220 400 Rio de Janeiro, Brazil
| | - Susanne Crocamo
- Núcleo de Pesquisa Clínica, Hospital de Câncer III, INCA, Rua Visconde de Santa Isabel, 274, Vila Isabel, 20 560 120 Rio de Janeiro, Brazil
| | - Caio A B Oliveira
- Departamento de Genética e Evolução, Universidade Federal de São Carlos, Rodovia Washington Luís, km 235, 13 560 300 São Carlos, São Paulo, Brazil
| | - Felipe R Teixeira
- Departamento de Genética e Evolução, Universidade Federal de São Carlos, Rodovia Washington Luís, km 235, 13 560 300 São Carlos, São Paulo, Brazil
| | - Raquel C Maia
- Laboratório de Hemato-Oncologia Celular e Molecular, Programa de Hemato-Oncologia Molecular, Instituto Nacional de Câncer (INCA), Praça da Cruz Vermelha, 23, 6° andar, Centro, 20 230 130 Rio de Janeiro, RJ, Brazil
| | - Gabriela Nestal de Moraes
- Laboratório de Hemato-Oncologia Celular e Molecular, Programa de Hemato-Oncologia Molecular, Instituto Nacional de Câncer (INCA), Praça da Cruz Vermelha, 23, 6° andar, Centro, 20 230 130 Rio de Janeiro, RJ, Brazil.
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3
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XAF1 directs apoptotic switch of p53 signaling through activation of HIPK2 and ZNF313. Proc Natl Acad Sci U S A 2014; 111:15532-7. [PMID: 25313037 DOI: 10.1073/pnas.1411746111] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
X-linked inhibitor of apoptosis (XIAP)-associated factor 1 (XAF1) is a tumor suppressor that is frequently inactivated in many human cancers. However, the molecular mechanism underlying its growth-inhibitory function remains largely unknown. Here, we report that XAF1 forms a positive feedback loop with p53 and acts as a molecular switch in p53-mediated cell-fate decisions favoring apoptosis over cell-cycle arrest. XAF1 binds directly to the N-terminal proline-rich domain of p53 and thus interferes with E3 ubiquitin ligase MDM2 binding and ubiquitination of p53. XAF1 stimulates homeodomain-interacting protein kinase 2 (HIPK2)-mediated Ser-46 phosphorylation of p53 by blocking E3 ubiquitin ligase Siah2 interaction with and ubiquitination of HIPK2. XAF1 also steps up the termination of p53-mediated cell-cycle arrest by activating zinc finger protein 313 (ZNF313), a p21(WAF1)-targeting ubiquitin E3 ligase. XAF1 interacts with p53, Siah2, and ZNF313 through the zinc finger domains 5, 6, and 7, respectively, and truncated XAF1 isoforms preferentially expressed in cancer cells fail to form a feedback loop with p53. Together, this study uncovers a novel role for XAF1 in p53 stress response, adding a new layer of complexity to the mechanisms by which p53 determines cell-fate decisions.
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Hernández-Jiménez M, Sacristán S, Morales C, García-Villanueva M, García-Fernández E, Alcázar A, González VM, Martín ME. Apoptosis-related proteins are potential markers of neonatal hypoxic-ischemic encephalopathy (HIE) injury. Neurosci Lett 2014; 558:143-8. [PMID: 24269372 DOI: 10.1016/j.neulet.2013.11.019] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Revised: 11/11/2013] [Accepted: 11/13/2013] [Indexed: 02/05/2023]
Abstract
Neonatal hypoxic-ischemic encephalopathy (HIE) causes high mortality and long-term morbidity rates. The magnitude of the neuronal damage depends on the duration and severity of the initial insult combined with the deleterious effects of reperfusion and apoptosis. Currently, a diagnosis of HIE is based largely on the neurological and histological findings. Therefore, the aim of this study was to identify apoptosis-related proteins that might serve as potential markers of HIE injury. As an initial step toward reaching this objective, we analyzed changes in protein levels in an in vitro model of hypoxia using antibody arrays, and we have identified changes in the expression level of two proteins involved in apoptosis, Smac-DIABLO and cathepsin D. We obtained brain sections from eight neonatal HIE patients and performed histological staining, TUNEL assays and Smac-DIABLO and cathepsin D immunolocalization. Our results revealed a high number of TUNEL-positive cells, including neurons, astrocytes and ependymal cells, in the various regions that were analyzed. Interestingly, many of the areas that were positive for TUNEL staining did not appear to be damaged in the histological evaluation. In addition, using immunostaining, we found that Smac-DIABLO and cathepsin D had the same regional distribution pattern. Taken together, these findings indicate that these two proteins could serve as markers to identify injured regions that might not to be detectable using histological observations alone.
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Affiliation(s)
| | - Silvia Sacristán
- Servicio de Neurobiología-Investigación, Hospital Ramón y Cajal-IRYCIS, 28034 Madrid, Spain
| | - Carmen Morales
- Servicio de Anatomía Patológica, Hospital Universitario La Paz, 28046 Madrid, Spain
| | | | | | - Alberto Alcázar
- Servicio de Bioquímica-Investigación, Hospital Ramón y Cajal-IRYCIS, 28034 Madrid, Spain
| | - Víctor M González
- Servicio de Bioquímica-Investigación, Hospital Ramón y Cajal-IRYCIS, 28034 Madrid, Spain
| | - M Elena Martín
- Servicio de Bioquímica-Investigación, Hospital Ramón y Cajal-IRYCIS, 28034 Madrid, Spain.
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Rami A, Kim M, Niquet J. Translocation of the Serine Protease Omi/HtrA2 from Mitochondria into the Cytosol Upon Seizure-Induced Hippocampal Injury in the Neonatal Rat Brain. Neurochem Res 2010; 35:2199-207. [DOI: 10.1007/s11064-010-0322-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/08/2010] [Indexed: 10/18/2022]
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Zhang W, Yang Y, Jiang B, Peng J, Tu S, Sardet C, Zhang Y, Pang R, Hung IF, Tan VPY, Lam CSC, Wang J, Wong BC. XIAP-associated factor 1 interacts with and attenuates the trans-activity of four and a Half LIM protein 2. Mol Carcinog 2010; 50:199-207. [DOI: 10.1002/mc.20705] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2010] [Revised: 09/14/2010] [Accepted: 10/18/2010] [Indexed: 11/11/2022]
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Siegelin MD, Reuss DE, Habel A, Herold-Mende C, von Deimling A. The flavonoid kaempferol sensitizes human glioma cells to TRAIL-mediated apoptosis by proteasomal degradation of survivin. Mol Cancer Ther 2008; 7:3566-74. [PMID: 19001439 DOI: 10.1158/1535-7163.mct-08-0236] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Resistance to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL/Apo2L) limits its potential as a drug for cancer therapy. Here, we report that kaempferol, a bioactive plant flavonoid, sensitizes U251 and U87 glioma cells to TRAIL-mediated apoptosis. In contrast, U373 cells are not affected by kaempferol treatment. Treatment of kaempferol alone for 24 h did not induce apoptosis in the cell lines. We provide evidence that TRAIL-induced apoptosis is partially driven by kaempferol-mediated reduction of survivin protein levels. On kaempferol treatment, proteasomal degradation of survivin was observed. Inhibition of proteasomal degradation with MG132 in kaempferol-treated cells restored survivin protein levels in both glial cell lines. Consequently, overexpression of survivin attenuated TRAIL-kaempferol-induced apoptosis. In addition, we show that kaempferol mediates down-regulation of phosphorylated Akt, thereby further reducing survivin protein level. Furthermore, the blockage of the serine/threonine kinase Akt activity by kaempferol is important for inhibition of survivin because active phosphorylated Akt enhances the stability of survivin. However, we also show that the combined treatment of TRAIL and kaempferol induces cleavage (activation) of caspase-8, thereby exerting a proapoptotic effect independent of survivin known not to inhibit caspase-8 activation. Other effects induced by kaempferol were suppression of X-linked inhibitor of apoptosis proteins as the antiapoptotic members of the Bcl-2 family, Bcl-2, Bcl-xL, and Mcl-1 in a concentration-dependent manner. In summary, we showed that suppression of survivin is an essential mechanism in TRAIL-kaempferol-mediated apoptosis.
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Affiliation(s)
- Markus D Siegelin
- Department of Neuropathology, University Hospital Heidelberg, Im Neuenheimer Feld 220, 69120 Heidelberg, Germany
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Siegelin MD, Reuss DE, Habel A, Rami A, von Deimling A. Quercetin promotes degradation of survivin and thereby enhances death-receptor-mediated apoptosis in glioma cells. Neuro Oncol 2008; 11:122-31. [PMID: 18971417 DOI: 10.1215/15228517-2008-085] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The flavonoid quercetin has been reported to inhibit the proliferation of cancer cells, whereas it has no effect on nonneoplastic cells. U87-MG, U251, A172, LN229, and U373 malignant glioma cells were treated with quercetin (50-200 microM). Quercetin did not cause cytotoxicity 24 h after treatment. Combining quercetin with tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) strongly augmented TRAIL-mediated apoptosis in U87-MG, U251, A172, and LN229 glioma cells; U373 cells could not be sensitized by quercetin to TRAIL-mediated apoptosis. TRAIL-induced apoptosis was enhanced by quercetin-induced reduction of survivin protein levels. Upon treatment with quercetin, the protein level of survivin was strongly suppressed in U87-MG, U251, and A172 but not in U373 glioma cells. Quercetin exposure resulted in proteasomal degradation of survivin. TRAIL-quercetin-induced apoptosis was markedly reduced by overexpression of survivin. In addition, upon treatment with quercetin, downregulation of survivin was also regulated by the Akt pathway. Taken together, the results of the present study suggest that quercetin sensitizes glioma cells to death-receptor-mediated apoptosis by suppression of inhibitor of the apoptosis protein survivin.
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Affiliation(s)
- Markus D Siegelin
- Department of Neuropathology, University Hospital Heidelberg, Heidelberg, Germany
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Shibata T, Noguchi T, Takeno S, Gabbert HE, Ramp U, Kawahara K. Disturbed XIAP and XAF1 Expression Balance Is an Independent Prognostic Factor in Gastric Adenocarcinomas. Ann Surg Oncol 2008; 15:3579-87. [DOI: 10.1245/s10434-008-0062-4] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2007] [Revised: 06/14/2008] [Accepted: 06/15/2008] [Indexed: 11/18/2022]
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Concomitant transitory up-regulation of X-linked inhibitor of apoptosis protein (XIAP) and the heterogeneous nuclear ribonucleoprotein C1-C2 in surviving cells during neuronal apoptosis. Neurochem Res 2008; 33:1859-68. [PMID: 18363099 DOI: 10.1007/s11064-008-9658-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2008] [Accepted: 03/07/2008] [Indexed: 10/22/2022]
Abstract
Although cap-dependent translation initiation is the prevalent mode of ribosome binding to mRNAs in eukaryotes, some mRNAs exhibit the ability to bypass the requirement for the cap structure. The translation of X-chromosome-linked inhibitor of apoptosis protein (XIAP) mRNA is controlled by an internal ribosome entry site (IRES) element, which requires the interaction of the heterogeneous nuclear ribonucleoprotein C1-C2 (hnRNP-C1/C2). We analyze, at the protein level, the time course and distribution of XIAP and hnRNP-C1/C2 upon ischemia in mice or staurosporine (STP)-induced apoptosis in HT22 cells. Both ischemia and STP induced a parallel upregulation of XIAP and hnRNP-C1/C2 protein levels in the penumbra and in HT22 cells. These results suggest that the increased levels of hnRNP C1/C2 may modulate XIAP translation, probably by interacting with the XIAP-IRES. The up-regulation of hnRNP-C1/C2 may foster the synthesis of XIAP as a protective pathway by which neurons try to counteract the initial deleterious effects of apoptosis.
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Nakka VP, Gusain A, Mehta SL, Raghubir R. Molecular mechanisms of apoptosis in cerebral ischemia: multiple neuroprotective opportunities. Mol Neurobiol 2008; 37:7-38. [PMID: 18066503 DOI: 10.1007/s12035-007-8013-9] [Citation(s) in RCA: 207] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2007] [Accepted: 11/05/2007] [Indexed: 12/18/2022]
Abstract
Cerebral ischemia/reperfusion (I/R) injury triggers multiple and distinct but overlapping cell signaling pathways, which may lead to cell survival or cell damage. There is overwhelming evidence to suggest that besides necrosis, apoptosis do contributes significantly to the cell death subsequent to I/R injury. Both extrinsic and intrinsic apoptotic pathways play a vital role, and upon initiation, these pathways recruit downstream apoptotic molecules to execute cell death. Caspases and Bcl-2 family members appear to be crucial in regulating multiple apoptotic cell death pathways initiated during I/R. Similarly, inhibitor of apoptosis family of proteins (IAPs), mitogen-activated protein kinases, and newly identified apoptogenic molecules, like second mitochondrial-activated factor/direct IAP-binding protein with low pI (Smac/Diablo), omi/high-temperature requirement serine protease A2 (Omi/HtrA2), X-linked mammalian inhibitor of apoptosis protein-associated factor 1, and apoptosis-inducing factor, have emerged as potent regulators of cellular apoptotic/antiapoptotic machinery. All instances of cell survival/death mechanisms triggered during I/R are multifaceted and interlinked, which ultimately decide the fate of brain cells. Moreover, apoptotic cross-talk between major subcellular organelles suggests that therapeutic strategies should be optimally directed at multiple targets/mechanisms for better therapeutic outcome. Based on the current knowledge, this review briefly focuses I/R injury-induced multiple mechanisms of apoptosis, involving key apoptotic regulators and their emerging roles in orchestrating cell death programme. In addition, we have also highlighted the role of autophagy in modulating cell survival/death during cerebral ischemia. Furthermore, an attempt has been made to provide an encouraging outlook on emerging therapeutic approaches for cerebral ischemia.
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Affiliation(s)
- Venkata Prasuja Nakka
- Division of Pharmacology, Central Drug Research Institute, Chatter Manzil Palace, POB-173, Lucknow, 226001, India
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Stoka V, Turk V, Bredesen DE. Differential regulation of Smac/DIABLO and Hsp-70 during brain maturation. Neuromolecular Med 2007; 9:255-63. [PMID: 17914183 PMCID: PMC2755584 DOI: 10.1007/s12017-007-8007-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2007] [Revised: 11/30/1999] [Accepted: 03/14/2007] [Indexed: 12/23/2022]
Abstract
The heat shock protein (Hsp) system is a cell defense mechanism constitutively expressed at the basal state and essential for cell survival in response to damaging stimuli. Apoptosis is a physiological cell death program that preserves tissue homeostasis. We investigated the intrinsic pathway of apoptosis at various stages of brain maturation in CD-1 mice, triggered by two mitochondrial proapoptotic proteins, cytochrome c and Smac/DIABLO, and the pathway's regulation by Hsp-70. Smac/DIABLO and Hsp-70 proteins were upregulated 2-fold and 1.5-3-fold, respectively, after birth. In contrast, in the presence of cytochrome c/2'-deoxyadenosine 5'-triphosphate (dATP), caspase activity in mouse brain cell-free extracts increased 90-fold and 61-fold, at fetal and neonatal stages, whereas no activation was detected 15 days postnatally or at any subsequent times. These results indicate that the activation pattern of the intrinsic pathway of apoptosis undergoes a marked shift during postnatal maturation.
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Affiliation(s)
- Veronika Stoka
- Buck Institute for Age Research, 8001 Redwood Blvd., Novato, CA 94945, USA
- Department of Biochemistry, Molecular and Structural Biology, J. Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia
| | - Vito Turk
- Department of Biochemistry, Molecular and Structural Biology, J. Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia
| | - Dale E. Bredesen
- Buck Institute for Age Research, 8001 Redwood Blvd., Novato, CA 94945, USA
- Department of Neurology, University of California, San Francisco, CA 94143, USA
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Focal cerebral ischemia induces upregulation of Beclin 1 and autophagy-like cell death. Neurobiol Dis 2007; 29:132-41. [PMID: 17936001 DOI: 10.1016/j.nbd.2007.08.005] [Citation(s) in RCA: 237] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2007] [Revised: 07/12/2007] [Accepted: 08/12/2007] [Indexed: 01/10/2023] Open
Abstract
Autophagy is a highly regulated cellular mechanism for the bulk degradation of cytoplasmic contents which seems to be implicated in a variety of physiological and pathological conditions relevant to neurological diseases. We were prompted to examine whether autophagy is involved in mechanisms of cell death after focal cerebral ischemia. To do so, we examined the protein level and distribution of Beclin 1 (Bcl2 interacting protein) and microtubule-associated protein 1 light chain 3 (LC3) which were previously found to promote autophagy. We found a dramatic elevation in Beclin 1 levels in the penumbra of rats challenged by cerebral ischemia. Beclin 1 elevations start at early stages postischemia (6 h) and it lasts for at least 48 h. A subpopulation of Beclin 1-upregulating cells is also expressing the active form of caspase-3. In addition, not all Beclin 1-upregulating cells display dense staining of LC3. Neuronal cells that overexpress Beclin 1 may exhibit damaged DNA but without changes in nuclear morphology, which indicates that not all the Beclin 1-upregulating cells are predestined to die. The upregulation of Beclin 1 and related changes of LC3 in the ischemic penumbra may represent enhanced autophagy either as a mechanism to recycle injured cells and reduce damage or a process leading to cell demise.
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Chung SK, Lee MG, Ryu BK, Lee JH, Han J, Byun DS, Chae KS, Lee KY, Jang JY, Kim HJ, Chi SG. Frequent alteration of XAF1 in human colorectal cancers: implication for tumor cell resistance to apoptotic stresses. Gastroenterology 2007; 132:2459-77. [PMID: 17570219 DOI: 10.1053/j.gastro.2007.04.024] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2006] [Accepted: 02/22/2007] [Indexed: 12/22/2022]
Abstract
BACKGROUND & AIMS X-linked inhibitor of apoptosis protein-associated factor 1 (XAF1) is a candidate tumor suppressor located at the chromosome 17p13 region, but the molecular basis underlying its inactivation in human tumors and growth-inhibiting function has not been well defined. We explored the candidacy of XAF1 as a suppressor in colorectal tumorigenesis. METHODS XAF1 expression was characterized by polymerase chain reaction-based cloning, isoform-specific polymerase chain reaction, ribonuclease protection, and immunoblot assays. Allelic loss of the gene was evaluated by loss of heterozygosity (LOH) assay, and promoter CG dinucleotide (CpG) site methylation was determined using bisulfite sequencing. The effect of XAF1 on tumor growth was examined using flow cytometry, terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling, colony formation, and viability assays. RESULTS Expression of 5 XAF1 variants including 2 novel transcripts was down-regulated concomitantly in 11 of 20 (55%) cell lines and 26 of 65 (40%) primary tumors. XAF1 reduction was tumor-specific and showed a correlation with advanced stage and high grade of tumor. LOH of the gene was found in 12 of 33 (36%) tumors. Promoter CpG site methylation was observed frequently in both cell lines and tumor tissues including many LOH tumors, suggesting that biallelic inactivation of XAF1 might be common in colorectal cancers. XAF1 expression suppressed tumor cell growth and enhanced cellular response to various apoptotic stimuli, such as 5-fluorouracil, etoposide, H(2)O(2), gamma-irradiation, ultraviolet, and tumor necrosis factor-alpha, whereas knockdown of its expression protected cells from the stresses. CONCLUSIONS Genetic and epigenetic alteration of XAF1 is a common event in colorectal tumorigenesis and contributes to the malignant tumor progression by providing survival advantages for tumor cells under various stress conditions.
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Affiliation(s)
- Sun-Ku Chung
- School of Life Sciences and Biotechnology, Korea University, Seoul, Korea
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15
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Rami A, Agarwal R, Spahn A. Synergetic effects of caspase 3 and mu-calpain in XIAP-breakdown upon focal cerebral ischemia. Neurochem Res 2007; 32:2072-9. [PMID: 17514421 DOI: 10.1007/s11064-007-9361-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2006] [Accepted: 04/20/2007] [Indexed: 01/26/2023]
Abstract
Dysregulation of apoptosis is involved in a wide spectrum of disease ranging from proliferative to neurodegenerative disorders. The recently discovered X-linked inhibitor of apoptosis protein (XIAP) is among the most potent inhibitors of apoptosis. This protein binds to and inhibits both initiator caspases and effector caspases such as caspase-3. The aim of this study was to investigate the relationships between XIAP-breakdown, caspase activation in the development of delayed infarct upon ischemia. We demonstrated that endogenous XIAP is cleaved at least into two fragments during reperfusion following the ischemic insult. The two fragments produced seem to be related to caspase-3 and mu-calpain activities, which are massively enhanced in tissues challenged by ischemia. Therefore, degradation of XIAP by mu-calpain in our system may decrease the activation threshold of caspase-3 normally held in check by the IAPs and/or lead to auto-activation of other caspases.
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Affiliation(s)
- Abdelhaq Rami
- Institute of Cellular and Molecular Anatomy, Dr. Senckenbergische Anatomie, Johann Wolfgang Goethe-University, Theodor-Stern-Kai 7, 60590, Frankfurt/Main, Germany.
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16
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Plesnila N, von Baumgarten L, Retiounskaia M, Engel D, Ardeshiri A, Zimmermann R, Hoffmann F, Landshamer S, Wagner E, Culmsee C. Delayed neuronal death after brain trauma involves p53-dependent inhibition of NF-kappaB transcriptional activity. Cell Death Differ 2007; 14:1529-41. [PMID: 17464322 DOI: 10.1038/sj.cdd.4402159] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Acute and chronic neurodegeneration, for example, following brain injury or Alzheimer's disease, is characterized by programmed death of neuronal cells. The present study addresses the role and interaction of p53- and NF-kappaB-dependent mechanisms in delayed neurodegeneration following traumatic brain injury (TBI). After experimental TBI in mice p53 rapidly accumulated in the injured brain tissue and translocated to the nucleus of damaged neurons, whereas NF-kappaB transcriptional activity simultaneously declined. Post-traumatic neurodegeneration correlated with the increase in p53 levels and was significantly reduced by the selective p53 inhibitor pifithrin-alpha (PFT). Strikingly, this protective effect was observed even when PFT treatment was delayed up to 6 h after trauma. Inhibition of p53 activity resulted in the concomitant increase in NF-kappaB transcriptional activity and upregulation of NF-kappaB-target proteins, for example X-chromosomal-linked inhibitor of apoptosis (XIAP). It is interesting to note that inhibition of XIAP abolished the neuroprotective effects of PFT in cultured neurons exposed to camptothecin, glutamate, or oxygen glucose deprivation. In conclusion, delayed neuronal cell death after brain trauma is mediated by p53-dependent mechanisms that involve inhibition of NF-kappaB transcriptional activity. Hence, p53 inhibition provides a promising approach for the treatment of acute brain injury, since it blocks apoptotic pathways and concomitantly triggers survival signaling with a therapeutic window relevant for clinical applications.
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Affiliation(s)
- N Plesnila
- Department of Neurosurgery, Institute for Surgical Research, University of Munich Medical Center - Grosshadern, Munich, Germany
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17
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Althaus J, Siegelin MD, Dehghani F, Cilenti L, Zervos AS, Rami A. The serine protease Omi/HtrA2 is involved in XIAP cleavage and in neuronal cell death following focal cerebral ischemia/reperfusion. Neurochem Int 2006; 50:172-80. [PMID: 16978742 DOI: 10.1016/j.neuint.2006.07.018] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2006] [Revised: 07/04/2006] [Accepted: 07/31/2006] [Indexed: 11/21/2022]
Abstract
Omi/HtrA2 is a pro-apoptotic mitochondrial serine protease involved in both forms of apoptosis, caspase-dependent as well as caspase-independent cell death. However, the impact of Omi/HtrA2 in the apoptotic cell machinery that takes place in vivo under pathological conditions such as cerebral ischemia remains unknown. The present study was monitored in order to examine whether Omi/HtrA2 plays a decisive role in apoptosis observed after focal cerebral ischemia in rats. Male adult rats were subjected to 90min of focal cerebral ischemia followed by reperfusion and treated with vehicle or ucf-101, a novel and specific Omi/HtrA2 inhibitor, prior reperfusion. Focal cerebral ischemia/reperfusion induced a mitochondrial up-regulation of Omi/HtrA2 and significantly increased cytosolic accumulation of Omi/HtrA2. Furthermore, ischemia led to activation of caspase-3 and degradation X-linked inhibitor of apoptosis protein (XIAP). Treatment of animals prior ischemia with ucf-101, the specific inhibitor of Omi/HtrA2, was able to (1) reduce the number of TUNEL-positive cells, to (2) attenuate the XIAP-breakdown and to (3) reduce the infarct size. This study shows for the first time that focal cerebral ischemia in rats results in Omi/HtrA2 translocation from the mitochondria to the cytosol, where it participates in neuronal cell death. Blocking the proteolytic activity of Omi/HtrA2 with specific inhibitors, such as the ucf-101, could be a novel way to afford neuroprotection and minimize cellular damage in cerebral ischemia/reperfusion.
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Affiliation(s)
- J Althaus
- Institut für Zelluläre und Molekulare Anatomie (Anatomie III), Johann Wolfgang von Goethe-Universität, Theodor-Stern-Kai 7, 60590 Franfurt, Main, Germany
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18
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Lee MG, Huh JS, Chung SK, Lee JH, Byun DS, Ryu BK, Kang MJ, Chae KS, Lee SJ, Lee CH, Kim JI, Chang SG, Chi SG. Promoter CpG hypermethylation and downregulation of XAF1 expression in human urogenital malignancies: implication for attenuated p53 response to apoptotic stresses. Oncogene 2006; 25:5807-22. [PMID: 16909101 DOI: 10.1038/sj.onc.1209867] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
XIAP-associated factor 1 (XAF1) is a new candidate tumor suppressor, which has been known to exert proapoptotic effects by interfering with the caspase-inhibiting activity of XIAP. To explore the XAF1's candidacy for a suppressor in urogenital tumorigenesis, we investigated the XAF1 status in a series of cancer cell lines and primary tumors derived from the bladder, kidney and prostate. Expression of XAF1 transcript was undetectable or extremely low in 60% (3/5) of bladder, 66% (10/15) of kidney, and 100% (3/3) prostate cancer cell lines. Abnormal reduction of XAF1 was also found in 33% (18/55) of primary bladder and 40% (8/20) of primary kidney tumors, and showed a correlation with advanced stage and high grade of bladder tumor. Hypermethylation at 14 CpG sites in the 5' proximal region of the XAF1 promoter was highly prevalent in cancers versus adjacent normal or benign tissues and tightly associated with reduced gene expression. XAF1 expression enhanced the apoptotic response of tumor cells to chemotherapeutic agents, such as etoposide or 5-FU. While XAF1 expression did not influence the subcellular distribution or expression of XIAP, it elevated the protein stability of p53 and its target gene expression. Moreover, the apoptosis-sensitizing and growth suppression function of XAF1 was markedly impeded by blockade of p53 function. Collectively, our study demonstrates that epigenetic alteration of XAF1 is frequent in human urogenital cancers and may contribute to the malignant progression of tumors by rendering tumor cells a survival advantage partially through the attenuated p53 response to apoptotic stresses.
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Affiliation(s)
- M-G Lee
- School of Life Sciences and Biotechnology, Korea University, Seoul, Korea
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19
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Xia Y, Novak R, Lewis J, Duckett CS, Phillips AC. Xaf1 can cooperate with TNFα in the induction of apoptosis, independently of interaction with XIAP. Mol Cell Biochem 2006; 286:67-76. [PMID: 16432762 DOI: 10.1007/s11010-005-9094-2] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2005] [Accepted: 11/28/2005] [Indexed: 10/25/2022]
Abstract
XIAP-associated factor 1 (Xaf1) binds XIAP and re-localizes it to the nucleus, thus inhibiting XIAP activity and enhancing apoptosis [1]. Xaf1 expression is reduced or absent in tumor samples and cell lines suggesting it may function as a tumor suppressor [2-5]. To further study Xaf1 function we generated Xaf1 inducible cells in the osteosarcoma cell line Saos-2. Despite Xaf1 inducing apoptosis that is dramatically enhanced by TNFalpha we find no evidence for an interaction between Xaf1 and XIAP. Furthermore, Xaf1 expression sensitized XIAP-/- fibroblasts to TNFalpha, demonstrating the existence of a novel mechanism of Xaf1 induced apoptosis distinct from antagonizing XIAP. Xaf1 expression promotes cytochrome c release that cannot be blocked by inhibition of caspase activity. This implicates a role for the mitochondrial apoptotic pathway, consistent with the ability of Bcl2 to block Xaf1 induced apoptosis. The data indicate that in Saos2 cells Xaf1 activates the mitochondrial apoptotic pathway to facilitate cytochrome c release, thus amplifying apoptotic signals from death receptors.
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Affiliation(s)
- Yan Xia
- Medical College of Georgia, Institute of Molecular Medicine and Genetics, CB2803, 1120 15th Street, Augusta, GA 30912, USA
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