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Huang X, Ji S, Bian C, Sun J, Ji H. The endoplasmic reticulum stress and B cell lymphoma-2 related ovarian killer participate in docosahexaenoic acid-induced adipocyte apoptosis in grass carp (Ctenopharyngodon idellus). J Anim Sci 2023; 101:skad101. [PMID: 37067261 PMCID: PMC10118398 DOI: 10.1093/jas/skad101] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Accepted: 04/12/2023] [Indexed: 04/18/2023] Open
Abstract
Docosahexaenoic acid (DHA) lessens adipose tissue lipid deposition partly by inducing adipocyte apoptosis in grass carp, but the underlying mechanism remains unclear. Endoplasmic reticulum (ER) stress and unfolded protein response (UPR) is the novel pathway for inducing apoptosis. This study aimed to explore the potential role of ER stress in DHA-induced apoptosis in grass carp (Ctenopharyngodon idellus) adipocytes. DHA induced apoptosis by deforming the nuclear envelope, condensing the chromatin, and increasing the expression of apoptosis-related proteins and genes in vivo and in vitro (P < 0.05). However, the ER stress inhibitor, 4-phenylbutyric acid (4-PBA), effectively suppressed DHA-induced apoptosis (P < 0.05), indicating that ER stress mediates DHA-induced adipocyte apoptosis. Furthermore, we observed that 200 μM DHA significantly up-regulates the transcripts of B cell lymphoma-2 (BCL-2) related ovarian killer (BOK) in vitro (P < 0.05). BOK is a pro-apoptotic protein in the BCL-2 family, which governs the mitochondria apoptosis pathway. Hence, we hypothesized that BOK might be an important linker between ER stress and apoptosis. We cloned and identified two grass carp BOK genes, BOKa and BOKb, which encode peptides of 213 and 216 amino acids, respectively. BOKa primarily localizes in ER and mitochondria in the cytoplasm, while BOKb localizes in the nucleus and cytoplasm of grass carp adipocytes. Moreover, 200 μM DHA treatment up-regulated the mRNA expression of BOKa and BOKb, whereas 4-PBA suppressed the DHA-induced expressions. These results raised the possibility that BOK participates in DHA-induced adipocyte apoptosis through ER stress signaling, in line with its localization in ER and mitochondria. Two UPR branches, the inositol-requiring enzyme 1 (IRE1α) and activating transcription factor 6 (ATF6) signaling pathways, are possibly important in DHA-induced adipocyte apoptosis, unlike protein kinase RNA-activated-like ER kinase. The study also emphasized the roles of BOKa and BOKb in IRE1α- and ATF6-mediated apoptosis. This work is the first to elucidate the importance of the ER stress-BOK pathway during adipocyte apoptosis in teleost.
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Affiliation(s)
- Xiaocheng Huang
- College of Animal Science and Technology, Northwest Agriculture and Forestry University, Yangling 712100, China
| | - Shanghong Ji
- College of Animal Science and Technology, Northwest Agriculture and Forestry University, Yangling 712100, China
| | - Chenchen Bian
- College of Animal Science and Technology, Northwest Agriculture and Forestry University, Yangling 712100, China
| | - Jian Sun
- College of Animal Science and Technology, Northwest Agriculture and Forestry University, Yangling 712100, China
| | - Hong Ji
- College of Animal Science and Technology, Northwest Agriculture and Forestry University, Yangling 712100, China
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2
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The cross-talk of autophagy and apoptosis in breast carcinoma: implications for novel therapies? Biochem J 2022; 479:1581-1608. [PMID: 35904454 DOI: 10.1042/bcj20210676] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2021] [Revised: 07/05/2022] [Accepted: 07/06/2022] [Indexed: 12/12/2022]
Abstract
Breast cancer is still the most common cancer in women worldwide. Resistance to drugs and recurrence of the disease are two leading causes of failure in treatment. For a more efficient treatment of patients, the development of novel therapeutic regimes is needed. Recent studies indicate that modulation of autophagy in concert with apoptosis induction may provide a promising novel strategy in breast cancer treatment. Apoptosis and autophagy are two tightly regulated distinct cellular processes. To maintain tissue homeostasis abnormal cells are disposed largely by means of apoptosis. Autophagy, however, contributes to tissue homeostasis and cell fitness by scavenging of damaged organelles, lipids, proteins, and DNA. Defects in autophagy promote tumorigenesis, whereas upon tumor formation rapidly proliferating cancer cells may rely on autophagy to survive. Given that evasion of apoptosis is one of the characteristic hallmarks of cancer cells, inhibiting autophagy and promoting apoptosis can negatively influence cancer cell survival and increase cell death. Hence, combination of antiautophagic agents with the enhancement of apoptosis may restore apoptosis and provide a therapeutic advantage against breast cancer. In this review, we discuss the cross-talk of autophagy and apoptosis and the diverse facets of autophagy in breast cancer cells leading to novel models for more effective therapeutic strategies.
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3
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Suraweera CD, Banjara S, Hinds MG, Kvansakul M. Metazoans and Intrinsic Apoptosis: An Evolutionary Analysis of the Bcl-2 Family. Int J Mol Sci 2022; 23:ijms23073691. [PMID: 35409052 PMCID: PMC8998228 DOI: 10.3390/ijms23073691] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 03/24/2022] [Accepted: 03/25/2022] [Indexed: 01/12/2023] Open
Abstract
The B-cell lymphoma-2 (Bcl-2) family is a group of genes regulating intrinsic apoptosis, a process controlling events such as development, homeostasis and the innate and adaptive immune responses in metazoans. In higher organisms, Bcl-2 proteins coordinate intrinsic apoptosis through their regulation of the integrity of the mitochondrial outer membrane; this function appears to have originated in the basal metazoans. Bcl-2 genes predate the cnidarian-bilaterian split and have been identified in porifera, placozoans and cnidarians but not ctenophores and some nematodes. The Bcl-2 family is composed of two groups of proteins, one with an α-helical Bcl-2 fold that has been identified in porifera, placozoans, cnidarians, and almost all higher bilaterians. The second group of proteins, the BH3-only group, has little sequence conservation and less well-defined structures and is found in cnidarians and most bilaterians, but not porifera or placozoans. Here we examine the evolutionary relationships between Bcl-2 proteins. We show that the structures of the Bcl-2-fold proteins are highly conserved over evolutionary time. Some metazoans such as the urochordate Oikopleura dioica have lost all Bcl-2 family members. This gene loss indicates that Bcl-2 regulated apoptosis is not an absolute requirement in metazoans, a finding mirrored in recent gene deletion studies in mice. Sequence analysis suggests that at least some Bcl-2 proteins lack the ability to bind BH3-only antagonists and therefore potentially have other non-apoptotic functions. By examining the foundations of the Bcl-2 regulated apoptosis, functional relationships may be clarified that allow us to understand the role of specific Bcl-2 proteins in evolution and disease.
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Affiliation(s)
- Chathura D. Suraweera
- Department of Biochemistry and Chemistry, La Trobe Institute for Molecular Science, La Trobe University, Bundoora, VIC 3086, Australia; (C.D.S.); (S.B.)
| | - Suresh Banjara
- Department of Biochemistry and Chemistry, La Trobe Institute for Molecular Science, La Trobe University, Bundoora, VIC 3086, Australia; (C.D.S.); (S.B.)
| | - Mark G. Hinds
- Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, VIC 3052, Australia
- Correspondence: (M.G.H.); (M.K.)
| | - Marc Kvansakul
- Department of Biochemistry and Chemistry, La Trobe Institute for Molecular Science, La Trobe University, Bundoora, VIC 3086, Australia; (C.D.S.); (S.B.)
- Correspondence: (M.G.H.); (M.K.)
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4
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The Mysteries around the BCL-2 Family Member BOK. Biomolecules 2020; 10:biom10121638. [PMID: 33291826 PMCID: PMC7762061 DOI: 10.3390/biom10121638] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 11/30/2020] [Accepted: 12/02/2020] [Indexed: 12/19/2022] Open
Abstract
BOK is an evolutionarily conserved BCL-2 family member that resembles the apoptotic effectors BAK and BAX in sequence and structure. Based on these similarities, BOK has traditionally been classified as a BAX-like pro-apoptotic protein. However, the mechanism of action and cellular functions of BOK remains controversial. While some studies propose that BOK could replace BAK and BAX to elicit apoptosis, others attribute to this protein an indirect way of apoptosis regulation. Adding to the debate, BOK has been associated with a plethora of non-apoptotic functions that makes this protein unpredictable when dictating cell fate. Here, we compile the current knowledge and open questions about this paradoxical protein with a special focus on its structural features as the key aspect to understand BOK biological functions.
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5
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Moravcikova E, Krepela E, Donnenberg VS, Donnenberg AD, Benkova K, Rabachini T, Fernandez-Marrero Y, Bachmann D, Kaufmann T. BOK displays cell death-independent tumor suppressor activity in non-small-cell lung carcinoma. Int J Cancer 2017; 141:2050-2061. [PMID: 28744854 DOI: 10.1002/ijc.30906] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Revised: 06/30/2017] [Accepted: 07/14/2017] [Indexed: 12/14/2022]
Abstract
As the genomic region containing the Bcl-2-related ovarian killer (BOK) locus is frequently deleted in certain human cancers, BOK is hypothesized to have a tumor suppressor function. In the present study, we analyzed primary non-small-cell lung carcinoma (NSCLC) tumors and matched lung tissues from 102 surgically treated patients. We show that BOK protein levels are significantly downregulated in NSCLC tumors as compared to lung tissues (p < 0.001). In particular, we found BOK downregulation in NSCLC tumors of grades two (p = 0.004, n = 35) and three (p = 0.031, n = 39) as well as in tumors with metastases to hilar (pN1) (p = 0.047, n = 31) and mediastinal/subcarinal lymph nodes (pN2) (p = 0.021, n = 18) as opposed to grade one tumors (p = 0.688, n = 7) and tumors without lymph node metastases (p = 0.112, n = 51). Importantly, in lymph node-positive patients, BOK expression greater than the median value was associated with longer survival (p = 0.002, Mantel test). Using in vitro approaches, we provide evidence that BOK overexpression is inefficient in inducing apoptosis but that it inhibits TGFβ-induced migration and epithelial-to-mesenchymal transition (EMT) in lung adenocarcinoma-derived A549 cells. We have identified epigenetic mechanisms, in particular BOK promoter methylation, as an important means to silence BOK expression in NSCLC cells. Taken together, our data point toward a novel mechanism by which BOK acts as a tumor suppressor in NSCLC by inhibiting EMT. Consequently, the restoration of BOK levels in low-BOK-expressing tumors might favor the overall survival of NSCLC patients.
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Affiliation(s)
- Erika Moravcikova
- Institute of Pharmacology, Faculty of Medicine, University of Bern, Bern, Switzerland.,Department of Cardiothoracic Surgery, School of Medicine, University of Pittsburgh, PA
| | - Evzen Krepela
- Institute of Biochemistry and Experimental Oncology, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Vera S Donnenberg
- Department of Cardiothoracic Surgery, School of Medicine, University of Pittsburgh, PA
| | | | - Kamila Benkova
- Department of Pathology, Hospital Bulovka, Prague, Czech Republic
| | - Tatiana Rabachini
- Institute of Pharmacology, Faculty of Medicine, University of Bern, Bern, Switzerland
| | | | - Daniel Bachmann
- Institute of Pharmacology, Faculty of Medicine, University of Bern, Bern, Switzerland
| | - Thomas Kaufmann
- Institute of Pharmacology, Faculty of Medicine, University of Bern, Bern, Switzerland
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6
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Einsele-Scholz S, Malmsheimer S, Bertram K, Stehle D, Johänning J, Manz M, Daniel PT, Gillissen BF, Schulze-Osthoff K, Essmann F. Bok is a genuine multi-BH-domain protein that triggers apoptosis in the absence of Bax and Bak. J Cell Sci 2016; 129:2213-23. [PMID: 27076518 DOI: 10.1242/jcs.181727] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Accepted: 04/11/2016] [Indexed: 12/15/2022] Open
Abstract
The pro-apoptotic multidomain Bcl-2 proteins Bax and Bak (also known as BAK1) are considered the gatekeepers of the intrinsic pathway of apoptosis by triggering the mitochondrial release of cytochrome c The role of the third Bax- and Bak-homologous multidomain protein Bok, however, is still unresolved. As cells doubly deficient for Bax and Bak are largely resistant to various apoptotic stimuli, it has been proposed that Bok is either dispensable for apoptosis or that its role is dependent on Bax and Bak. Here, we demonstrate, in several cell systems, that Bok efficiently induces cytochrome c release and apoptosis even in the complete absence of both Bak and Bax. Moreover, modulation of endogenous Bok levels affects the apoptosis response. By RNA interference and targeted deletion of the Bok gene, we demonstrate that Bok can significantly influence the apoptotic response to chemotherapeutic drugs in ovarian carcinoma cells. Hence, our results not only establish Bok as a Bak- and Bax-independent apoptosis inducer, but also suggest a potential impact of Bok expression in ovarian cancer therapy.
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Affiliation(s)
- Stephanie Einsele-Scholz
- Department of Molecular Medicine, Interfaculty Institute for Biochemistry, Eberhard Karls University, Tübingen 72076, Germany
| | - Silke Malmsheimer
- Department of Molecular Medicine, Interfaculty Institute for Biochemistry, Eberhard Karls University, Tübingen 72076, Germany
| | - Katrin Bertram
- Department of Molecular Medicine, Interfaculty Institute for Biochemistry, Eberhard Karls University, Tübingen 72076, Germany
| | - Daniel Stehle
- Department of Molecular Medicine, Interfaculty Institute for Biochemistry, Eberhard Karls University, Tübingen 72076, Germany
| | - Janina Johänning
- Department of Molecular Medicine, Interfaculty Institute for Biochemistry, Eberhard Karls University, Tübingen 72076, Germany
| | - Marianne Manz
- Department of Molecular Medicine, Interfaculty Institute for Biochemistry, Eberhard Karls University, Tübingen 72076, Germany
| | - Peter T Daniel
- Department of Hematology, Oncology and Tumor Immunology, University Medical Center Charité, Humboldt University, Berlin 13125, Germany German Cancer Consortium (DKTK) and German Cancer Research Center (DKFZ), Heidelberg 69120, Germany
| | - Bernhard F Gillissen
- Department of Hematology, Oncology and Tumor Immunology, University Medical Center Charité, Humboldt University, Berlin 13125, Germany German Cancer Consortium (DKTK) and German Cancer Research Center (DKFZ), Heidelberg 69120, Germany
| | - Klaus Schulze-Osthoff
- Department of Molecular Medicine, Interfaculty Institute for Biochemistry, Eberhard Karls University, Tübingen 72076, Germany German Cancer Consortium (DKTK) and German Cancer Research Center (DKFZ), Heidelberg 69120, Germany
| | - Frank Essmann
- Department of Molecular Medicine, Interfaculty Institute for Biochemistry, Eberhard Karls University, Tübingen 72076, Germany German Cancer Consortium (DKTK) and German Cancer Research Center (DKFZ), Heidelberg 69120, Germany
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7
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Chaurasia MK, Palanisamy R, Harikrishnan R, Arasu MV, Al-Dhabi NA, Arockiaraj J. Molecular profiles and pathogen-induced transcriptional responses of prawn B cell lymphoma-2 related ovarian killer protein (BOK). FISH & SHELLFISH IMMUNOLOGY 2015; 45:598-607. [PMID: 25982403 DOI: 10.1016/j.fsi.2015.04.031] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Revised: 04/20/2015] [Accepted: 04/27/2015] [Indexed: 06/04/2023]
Abstract
In this study, we have reported a molecular characterization of the first B cell lymphoma-2 (BCL-2) related ovarian killer protein (BOK) from freshwater prawn Macrobrachium rosenbergii (Mr). BOK is a novel pro-apoptotic protein of the BCL-2 family that entails in mediating apoptosis to remove cancer cells. A cDNA sequence of MrBOK was identified from the prawn cDNA library and its full length was obtained by internal sequencing. The coding region of MrBOK yields a polypeptide of 291 amino acids. The analysis revealed that MrBOK contains a transmembrane helix at V(261)-L(283) and a putative BCL-2 family domain at V(144)-W(245). MrBOK also possessed four putative BCL-2 homology domains including BH1, BH2, BH3 and weak BH4. The BH3 contains 21 binding sites and among them five residues are highly conserved with the aligned BOK proteins. The homology analysis showed that MrBOK shared maximum similarity with the Caligus rogercresseyi BOK A. The topology of the phylogenetic tree was classified into nine sister groups which includes BOK, BAK, BAX, BAD, BCL-2, BCL-XL, NR13 and MCL members. The BOK protein group further sub-grouped into vertebrate and invertebrate BOK, wherein MrBOK located within insect monophyletic clad of invertebrate BOK. The secondary structural analysis showed that MrBOK contains 11 α-helices (52.2%) which are connected over random coils (47.7%). The 3D structure of MrBOK showed three central helices (α6, α7 and α8) which formed the core of the protein and are flanked on one side by α1, α2 and α3, and on the other side by α4, α5 and α11. MrBOK mRNA is expressed most abundantly (P < 0.05) in ovary compared to other tissues taken for analysis. Hence ovary was selected to study the possible roles of MrBOK mRNA regulation upon bacterial (Aeromonas hydrophila and Vibrio harveyi) and viral [white spot syndrome virus (WSSV) and M. rosenbergii nodovirus] infection. During bacterial and viral infection, the highest MrBOK mRNA transcription was varied at different time points. In bacterial infected ovary tissue, the highest mRNA expression was at 24 h post-infection, whereas in viral infection, the expression was highest at 48 h post-infection. Thus we can conclude that MrBOK functions as an apoptotic protein in intracellular programmed cell-death pathway to counteract the anti-apoptotic proteins released by bacterial and viral pathogens at the time of infection. This is the first study that emphasizes the importance of BOK during bacterial and viral infection in crustacean.
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Affiliation(s)
- Mukesh Kumar Chaurasia
- Division of Fisheries Biotechnology & Molecular Biology, Research Department of Biotechnology, Faculty of Science and Humanities, SRM University, Kattankulathur, 603 203, Chennai, Tamil Nadu, India
| | - Rajesh Palanisamy
- Division of Fisheries Biotechnology & Molecular Biology, Research Department of Biotechnology, Faculty of Science and Humanities, SRM University, Kattankulathur, 603 203, Chennai, Tamil Nadu, India
| | - Ramasamy Harikrishnan
- Department of Zoology, Pachaiyappa's College for Men, Kanchipuram, 631 501, Tamil Nadu, India
| | - Mariadhas Valan Arasu
- Department of Botany and Microbiology, Addiriyah Chair for Environmental Studies, College of Science, King Saud University, P. O. Box 2455, Riyadh, 11451, Saudi Arabia
| | - Naif Abdullah Al-Dhabi
- Department of Botany and Microbiology, Addiriyah Chair for Environmental Studies, College of Science, King Saud University, P. O. Box 2455, Riyadh, 11451, Saudi Arabia
| | - Jesu Arockiaraj
- Division of Fisheries Biotechnology & Molecular Biology, Research Department of Biotechnology, Faculty of Science and Humanities, SRM University, Kattankulathur, 603 203, Chennai, Tamil Nadu, India.
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8
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Chi X, Kale J, Leber B, Andrews DW. Regulating cell death at, on, and in membranes. BIOCHIMICA ET BIOPHYSICA ACTA 2014; 1843:2100-13. [PMID: 24927885 DOI: 10.1016/j.bbamcr.2014.06.002] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Revised: 05/29/2014] [Accepted: 06/03/2014] [Indexed: 11/17/2022]
Abstract
Bcl-2 family proteins are central regulators of apoptosis. Various family members are located in the cytoplasm, endoplasmic reticulum, and mitochondrial outer membrane in healthy cells. However during apoptosis most of the interactions between family members that determine the fate of the cell occur at the membranes of intracellular organelles. It has become evident that interactions with membranes play an active role in the regulation of Bcl-2 family protein interactions. Here we provide an overview of various models proposed to explain how the Bcl-2 family regulates apoptosis and discuss how membrane binding affects the structure and function of each of the three categories of Bcl-2 proteins (pro-apoptotic, pore-forming, and anti-apoptotic). We also examine how the Bcl-2 family regulates other aspects of mitochondrial and ER physiology relevant to cell death.
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Affiliation(s)
- Xiaoke Chi
- Department of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario L8N 3Z5, Canada
| | - Justin Kale
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario L8N 3Z5, Canada
| | - Brian Leber
- Department of Medicine, McMaster University, Hamilton, Ontario L8N 3Z5, Canada
| | - David W Andrews
- Department of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario L8N 3Z5, Canada; Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario L8N 3Z5, Canada; Biological Sciences, Sunnybrook Research Institute, Toronto, Ontario M4N 3M5, Canada; Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada.
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9
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Abstract
Pre-eclampsia, a disorder of pregnancy, is characterized by placental hypoxia and cell death. Hypoxia shifts the intricate balance between death-inducing BOK and survival-promoting MCL1 towards BOK, thereby triggering placental cell death. Here, we show that BOK is a direct target of HIF.
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10
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Ye P, Zhao L, McGirr C, Gonda TJ. MYB down-regulation enhances sensitivity of U937 myeloid leukemia cells to the histone deacetylase inhibitor LBH589 in vitro and in vivo. Cancer Lett 2014; 343:98-106. [PMID: 24075958 DOI: 10.1016/j.canlet.2013.09.022] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Revised: 09/16/2013] [Accepted: 09/18/2013] [Indexed: 11/30/2022]
Abstract
The effect of combining MYB suppression with the histone deacetylase inhibitor LBH589 was studied in human myeloid leukemia cell lines. MYB knockdown inhibited proliferation and induced apoptosis in U937 and K562 cells in vitro, and also sensitized both to the pro-apoptotic effect of LBH589. This was accompanied by enhanced expression of the pro-apoptotic BCL2 family members BOK and BIM. U937 cells carrying inducible MYB shRNA were also transplanted into NOD/SCID mice. The combination of MYB knockdown and LBH589 prolonged survival compared to either treatment alone, suggesting that further development of such combinations might lead to effective and safe leukemia therapies.
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Affiliation(s)
- Ping Ye
- School of Pharmacy, The University of Queensland, Brisbane, Queensland 4102, Australia; The University of Queensland Diamantina Institute, Brisbane, Queensland 4102, Australia
| | - Liang Zhao
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Crystal McGirr
- School of Pharmacy, The University of Queensland, Brisbane, Queensland 4102, Australia; The University of Queensland Diamantina Institute, Brisbane, Queensland 4102, Australia
| | - Thomas J Gonda
- School of Pharmacy, The University of Queensland, Brisbane, Queensland 4102, Australia; The University of Queensland Diamantina Institute, Brisbane, Queensland 4102, Australia.
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11
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Echeverry N, Bachmann D, Ke F, Strasser A, Simon HU, Kaufmann T. Intracellular localization of the BCL-2 family member BOK and functional implications. Cell Death Differ 2013; 20:785-99. [PMID: 23429263 PMCID: PMC3647236 DOI: 10.1038/cdd.2013.10] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The pro-apoptotic BCL-2 family member BOK is widely expressed and resembles the multi-BH domain proteins BAX and BAK based on its amino acid sequence. The genomic region encoding BOK was reported to be frequently deleted in human cancer and it has therefore been hypothesized that BOK functions as a tumor suppressor. However, little is known about the molecular functions of BOK. We show that enforced expression of BOK activates the intrinsic (mitochondrial) apoptotic pathway in BAX/BAK-proficient cells but fails to kill cells lacking both BAX and BAK or sensitize them to cytotoxic insults. Interestingly, major portions of endogenous BOK are localized to and partially inserted into the membranes of the Golgi apparatus as well as the endoplasmic reticulum (ER) and associated membranes. The C-terminal transmembrane domain of BOK thereby constitutes a 'tail-anchor' specific for targeting to the Golgi and ER. Overexpression of full-length BOK causes early fragmentation of ER and Golgi compartments. A role for BOK on the Golgi apparatus and the ER is supported by an abnormal response of Bok-deficient cells to the Golgi/ER stressor brefeldin A. Based on these results, we propose that major functions of BOK are exerted at the Golgi and ER membranes and that BOK induces apoptosis in a manner dependent on BAX and BAK.
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Affiliation(s)
- N Echeverry
- Institute of Pharmacology, University of Bern, Bern, Switzerland
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12
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BCL-2 family member BOK is widely expressed but its loss has only minimal impact in mice. Cell Death Differ 2012; 19:915-25. [PMID: 22281706 DOI: 10.1038/cdd.2011.210] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
BOK/MTD was discovered as a protein that binds to the anti-apoptotic Bcl-2 family member MCL-1 and shares extensive amino-acid sequence similarity to BAX and BAK, which are essential for the effector phase of apoptosis. Therefore, and on the basis of its reported expression pattern, BOK is thought to function in a BAX/BAK-like pro-apoptotic manner in female reproductive tissues. In order to determine the function of BOK, we examined its expression in diverse tissues and investigated the consequences of its loss in Bok(-/-) mice. We confirmed that Bok mRNA is prominently expressed in the ovaries and uterus, but also observed that it is present at readily detectable levels in several other tissues such as the brain and myeloid cells. Bok(-/-) mice were produced at the expected Mendelian ratio, appeared outwardly normal and proved fertile. Histological examination revealed that major organs in Bok(-/-) mice displayed no morphological aberrations. Although several human cancers have somatically acquired copy number loss of the Bok gene and BOK is expressed in B lymphoid cells, we found that its deficiency did not accelerate lymphoma development in Eμ-Myc transgenic mice. Collectively, these results indicate that Bok may have a role that largely overlaps with that of other members of the Bcl-2 family, or may have a function restricted to specific stress stimuli and/or tissues.
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13
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Sassone J, Colciago C, Marchi P, Ascardi C, Alberti L, Di Pardo A, Zippel R, Sipione S, Silani V, Ciammola A. Mutant Huntingtin induces activation of the Bcl-2/adenovirus E1B 19-kDa interacting protein (BNip3). Cell Death Dis 2011; 1:e7. [PMID: 21364626 PMCID: PMC3032515 DOI: 10.1038/cddis.2009.6] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Huntington's disease (HD) is a neurodegenerative disorder characterized by progressive neuronal death in the basal ganglia and cortex. Although increasing evidence supports a pivotal role of mitochondrial dysfunction in the death of patients' neurons, the molecular bases for mitochondrial impairment have not been elucidated. We provide the first evidence of an abnormal activation of the Bcl-2/adenovirus E1B 19-kDa interacting protein 3 (BNip3) in cells expressing mutant Huntingtin. In this study, we show an abnormal accumulation and dimerization of BNip3 in the mitochondria extracted from human HD muscle cells, HD model cell cultures and brain tissues from HD model mice. Importantly, we have shown that blocking BNip3 expression and dimerization restores normal mitochondrial potential in human HD muscle cells. Our data shed light on the molecular mechanisms underlying mitochondrial dysfunction in HD and point to BNip3 as a new potential target for neuroprotective therapy in HD.
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Affiliation(s)
- J Sassone
- Department of Neurology and Laboratory of Neuroscience, Centro Dino Ferrari Università degli Studi di Milano-IRCCS Istituto Auxologico Italiano, Milano, Italy
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14
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Jääskeläinen M, Nieminen A, Pökkylä RM, Kauppinen M, Liakka A, Heikinheimo M, Vaskivuo TE, Klefström J, Tapanainen JS. Regulation of cell death in human fetal and adult ovaries--role of Bok and Bcl-X(L). Mol Cell Endocrinol 2010; 330:17-24. [PMID: 20673843 DOI: 10.1016/j.mce.2010.07.020] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2010] [Revised: 06/22/2010] [Accepted: 07/19/2010] [Indexed: 11/23/2022]
Abstract
Of eight million oocytes formed in fetal ovaries, only 400 are ovulated and the rest are degraded via apoptosis. Studies in rodents suggest an important role for Bok and Bcl-X(L) in ovarian apoptosis, but their expression patterns and roles in human ovaries are not well known. Protein expression of Bok and Bcl-X(L) as well as the death pathway effectors TNF and caspase-3 were determined in an important collection of samples consisting of human fetal and adult ovaries. A penetrant expression of Bok, Bcl-X(L), TNF and full length and cleaved caspase-3 were characterized in fetal ovaries, with specific patterns in oocytes and pre-granulosa/granulosa cells. Bok and Bcl-X(L) were detected also in adult ovaries. Lentiviral shRNA delivery demonstrated that loss of Bok markedly reduces vulnerability to apoptosis and, conversely, loss of Bcl-X(L) increases apoptosis in human granulosa tumour cell line. The results suggest important roles for Bok and Bcl-X(L) in human ovarian development, follicle maturation and apoptosis.
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Ray JE, Garcia J, Jurisicova A, Caniggia I. Mtd/Bok takes a swing: proapoptotic Mtd/Bok regulates trophoblast cell proliferation during human placental development and in preeclampsia. Cell Death Differ 2009; 17:846-59. [DOI: 10.1038/cdd.2009.167] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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16
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Chapman EJ, Williams SV, Platt FM, Hurst CD, Chambers P, Roberts P, Knowles MA. Integrated genomic and transcriptional analysis of the in vitro evolution of telomerase-immortalized urothelial cells (TERT-NHUC). Genes Chromosomes Cancer 2009; 48:694-710. [PMID: 19405089 DOI: 10.1002/gcc.20672] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Much progress has been made in identifying the molecular genetic alterations that occur in bladder cancer. However, in many cases the genes targeted by these alterations are not known. Telomerase immortalized human urothelial cells (TERT-NHUC) are a useful resource for in vitro studies of genes involved in urothelial transformation. When cultured under standard conditions they remain genetically stable but when cultured under low-density conditions they exhibit genetic instability and acquire chromosomal alterations. TERT-NHUC from three donors were cultured at low plating density and examined at four time-points during a culture period of 600 days. Analyses included population doubling kinetics, array-based CGH (aCGH), chromosome counts, fluorescence in situ hybridization (FISH), mutation analysis, Affymetrix gene expression analysis, Western blotting for p16, anchorage-independent growth and tumorigenicity assays. Alterations acquired during continued culture of TERT-NHUC at low density (TERT-NHUC-L) included some observed in urothelial carcinoma (UC) cell lines and primary UC. Examination of gene expression in TERT-NHUC with distinct acquired genetic aberrations may pinpoint genes targeted by these alterations. Data from an aCGH study of UC cell lines and primary tumors were examined for changes in chromosomal regions that also showed alterations in TERT-NHUC-L. Loss of a region on 2q including BOK was identified in UC cell lines and primary tumors. DNER and FRAS1 were identified as potential candidate genes, whose expression is altered independently of the acquisition of any genetic event.
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Affiliation(s)
- Emma J Chapman
- Cancer Research UK Clinical Centre, St James's University Hospital, Leeds LS97TF, UK
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17
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Abstract
BCL-2 family proteins, which have either pro- or anti-apoptotic activities, have been studied intensively for the past decade owing to their importance in the regulation of apoptosis, tumorigenesis and cellular responses to anti-cancer therapy. They control the point of no return for clonogenic cell survival and thereby affect tumorigenesis and host-pathogen interactions and regulate animal development. Recent structural, phylogenetic and biological analyses, however, suggest the need for some reconsideration of the accepted organizational principles of the family and how the family members interact with one another during programmed cell death. Although these insights into interactions among BCL-2 family proteins reveal how these proteins are regulated, a unifying hypothesis for the mechanisms they use to activate caspases remains elusive.
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Soleymanlou N, Jurisicova A, Wu Y, Chijiiwa M, Ray JE, Detmar J, Todros T, Zamudio S, Post M, Caniggia I. Hypoxic switch in mitochondrial myeloid cell leukemia factor-1/Mtd apoptotic rheostat contributes to human trophoblast cell death in preeclampsia. THE AMERICAN JOURNAL OF PATHOLOGY 2007; 171:496-506. [PMID: 17600131 PMCID: PMC1934524 DOI: 10.2353/ajpath.2007.070094] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Preeclampsia, a disorder of pregnancy, is characterized by increased trophoblast cell death and altered trophoblast-mediated remodeling of myometrial spiral arteries resulting in reduced uteroplacental perfusion. Mitochondria-associated Bcl-2 family members are important regulators of programed cell death. The mechanism whereby hypoxia alters the mitochondrial apoptotic rheostat is essential to our understanding of placental disease. Herein, myeloid cell leukemia factor-1 (Mcl-1) isoform expression was examined in physiological/pathological models of placental hypoxia. Preeclamptic placentae were characterized by caspase-dependent cleavage of death-suppressing Mcl-1L and switch toward cell death-inducing Mcl-1S. In vitro, Mcl-1L cleavage was induced by hypoxia-reoxygenation in villous explants, whereas Mcl-1L overexpression under hypoxia-reoxygenation rescued trophoblast cells from undergoing apoptosis. Cleavage was mediated by caspase-3/-7 because pharmacological caspase inhibition prevented this process. Altitude-induced chronic hypoxia was characterized by expression of Mcl-1L; resulting in a reduction of apoptotic markers (cleaved caspase-3/-8 and p85 poly-ADP-ribose polymerase). Moreover, in both physiological (explants and high altitude) and pathological (preeclampsia) placental hypoxia, decreased trophoblast syncytin expression was observed. Hence, although both pathological and physiological placental hypoxia are associated with slowed trophoblast differentiation, trophoblast apoptosis is only up-regulated in preeclampsia, because of a hypoxia-reoxygenation-induced switch in generation of proapoptotic Mcl-1 isoforms.
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19
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Abstract
Irrespective of the morphological features of end-stage cell death (that may be apoptotic, necrotic, autophagic, or mitotic), mitochondrial membrane permeabilization (MMP) is frequently the decisive event that delimits the frontier between survival and death. Thus mitochondrial membranes constitute the battleground on which opposing signals combat to seal the cell's fate. Local players that determine the propensity to MMP include the pro- and antiapoptotic members of the Bcl-2 family, proteins from the mitochondrialpermeability transition pore complex, as well as a plethora of interacting partners including mitochondrial lipids. Intermediate metabolites, redox processes, sphingolipids, ion gradients, transcription factors, as well as kinases and phosphatases link lethal and vital signals emanating from distinct subcellular compartments to mitochondria. Thus mitochondria integrate a variety of proapoptotic signals. Once MMP has been induced, it causes the release of catabolic hydrolases and activators of such enzymes (including those of caspases) from mitochondria. These catabolic enzymes as well as the cessation of the bioenergetic and redox functions of mitochondria finally lead to cell death, meaning that mitochondria coordinate the late stage of cellular demise. Pathological cell death induced by ischemia/reperfusion, intoxication with xenobiotics, neurodegenerative diseases, or viral infection also relies on MMP as a critical event. The inhibition of MMP constitutes an important strategy for the pharmaceutical prevention of unwarranted cell death. Conversely, induction of MMP in tumor cells constitutes the goal of anticancer chemotherapy.
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Affiliation(s)
- Guido Kroemer
- Institut Gustave Roussy, Institut National de la Santé et de la Recherche Médicale Unit "Apoptosis, Cancer and Immunity," Université de Paris-Sud XI, Villejuif, France
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20
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Sandau US, Handa RJ. Glucocorticoids exacerbate hypoxia-induced expression of the pro-apoptotic gene Bnip3 in the developing cortex. Neuroscience 2006; 144:482-94. [PMID: 17110051 PMCID: PMC1832146 DOI: 10.1016/j.neuroscience.2006.10.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2006] [Revised: 09/28/2006] [Accepted: 10/07/2006] [Indexed: 12/17/2022]
Abstract
Neonatal administration of the synthetic glucocorticoid, dexamethasone (DEX) retards brain growth, alters adult behaviors and induces cell death in the rat brain, thereby implicating glucocorticoids as developmentally neuroendangering compounds. Glucocorticoids also increase expression of pro-apoptotic Bcl-2 family members and exacerbate expression of hypoxic responsive genes. Bnip3 is a pro-apoptotic Bcl-2 family member that is upregulated in response to hypoxia. In these studies, we investigated the interactions of glucocorticoid receptor and hypoxia in the regulation of Bnip3 mRNA in cortical neurons. Using quantitative real time reverse transcription-polymerase chain reaction, we found that DEX treatment of postnatal days 4-6 rat pups caused a significant increase in Bnip3 mRNA expression compared with vehicle controls. A significant increase in Bnip3 mRNA was also measured in primary cortical neurons 72 h after treatment with RU28362, a glucocorticoid receptor selective agonist. In primary cortical neurons, hypoxia increased Bnip3 mRNA expression and this was exacerbated with RU28362 treatment. To elucidate the mechanism of glucocorticoid- and hypoxia-mediated regulation of Bnip3 transcription, a Bnip3 promoter-luciferase reporter construct was utilized in primary cortical neurons. Upregulation of the Bnip3 promoter was mediated by a single glucocorticoid response element and a hypoxic response element. Bnip3 overexpression in primary cortical neurons significantly increased cell death, which is dependent on the Bnip3 transmembrane domain. However, despite the increased expression of Bnip3 following glucocorticoid and hypoxia treatment, corresponding decreases in cell survival were minimal. These studies identify a novel pathway in the developing cortex through which glucocorticoids may enhance a metabolic insult, such as hypoxia.
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Affiliation(s)
- U S Sandau
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523-1617, USA
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Holtz WA, Turetzky JM, Jong YJI, O'Malley KL. Oxidative stress-triggered unfolded protein response is upstream of intrinsic cell death evoked by parkinsonian mimetics. J Neurochem 2006; 99:54-69. [PMID: 16987235 DOI: 10.1111/j.1471-4159.2006.04025.x] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Oxidative stress is a key player in a variety of neurodegenerative disorders including Parkinson's disease. Widely used as a parkinsonian mimetic, 6-hydroxydopamine (6-OHDA) generates reactive oxygen species (ROS) as well as coordinated changes in gene transcription associated with the unfolded protein response (UPR) and apoptosis. Whether 6-OHDA-induced UPR activation is dependent on ROS has not yet been determined. The present study used molecular indicators of oxidative stress to place 6-OHDA-generated ROS upstream of the appearance of UPR markers such as activating transcription factor 3 (ATF3) and phosphorylated stress-activated protein kinase (SAPK/JNK) signaling molecules. Antioxidants completely blocked 6-OHDA-mediated UPR activation and rescued cells from toxicity. Moreover, cytochrome c release from mitochondria was observed after the appearance of early UPR markers, suggesting that cellular stress pathways are responsible for its release. Mechanistically, the 6-OHDA-induced UPR was independent of intracellular calcium changes. Rather, evidence of protein oxidation was observed before the expression of UPR markers, suggesting that the rapid accumulation of damaged proteins triggered cell stress/UPR. Taken together, 6-OHDA-mediated cell death in dopaminergic cells proceeds via ROS-dependent UPR up-regulation which leads to an interaction with the intrinsic mitochondrial pathway and downstream caspase activation.
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Affiliation(s)
- William A Holtz
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St Louis, Missouri 63110, USA
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