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Samaržija I, Dekanić A, Humphries JD, Paradžik M, Stojanović N, Humphries MJ, Ambriović-Ristov A. Integrin Crosstalk Contributes to the Complexity of Signalling and Unpredictable Cancer Cell Fates. Cancers (Basel) 2020; 12:E1910. [PMID: 32679769 PMCID: PMC7409212 DOI: 10.3390/cancers12071910] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 07/10/2020] [Accepted: 07/12/2020] [Indexed: 12/12/2022] Open
Abstract
Integrins are heterodimeric cell surface receptors composed of α and β subunits that control adhesion, proliferation and gene expression. The integrin heterodimer binding to ligand reorganises the cytoskeletal networks and triggers multiple signalling pathways that can cause changes in cell cycle, proliferation, differentiation, survival and motility. In addition, integrins have been identified as targets for many different diseases, including cancer. Integrin crosstalk is a mechanism by which a change in the expression of a certain integrin subunit or the activation of an integrin heterodimer may interfere with the expression and/or activation of other integrin subunit(s) in the very same cell. Here, we review the evidence for integrin crosstalk in a range of cellular systems, with a particular emphasis on cancer. We describe the molecular mechanisms of integrin crosstalk, the effects of cell fate determination, and the contribution of crosstalk to therapeutic outcomes. Our intention is to raise awareness of integrin crosstalk events such that the contribution of the phenomenon can be taken into account when researching the biological or pathophysiological roles of integrins.
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Affiliation(s)
- Ivana Samaržija
- Laboratory for Cell Biology and Signalling, Division of Molecular Biology, Ruđer Bošković Institute, 10000 Zagreb, Croatia; (I.S.); (M.P.); (N.S.)
| | - Ana Dekanić
- Laboratory for Protein Dynamics, Division of Molecular Medicine, Ruđer Bošković Institute, 10000 Zagreb, Croatia;
| | - Jonathan D. Humphries
- Wellcome Centre for Cell-Matrix Research, Faculty of Biology, Medicine & Health, University of Manchester, Manchester M13 9PT, UK; (J.D.H.); (M.J.H.)
| | - Mladen Paradžik
- Laboratory for Cell Biology and Signalling, Division of Molecular Biology, Ruđer Bošković Institute, 10000 Zagreb, Croatia; (I.S.); (M.P.); (N.S.)
| | - Nikolina Stojanović
- Laboratory for Cell Biology and Signalling, Division of Molecular Biology, Ruđer Bošković Institute, 10000 Zagreb, Croatia; (I.S.); (M.P.); (N.S.)
| | - Martin J. Humphries
- Wellcome Centre for Cell-Matrix Research, Faculty of Biology, Medicine & Health, University of Manchester, Manchester M13 9PT, UK; (J.D.H.); (M.J.H.)
| | - Andreja Ambriović-Ristov
- Laboratory for Cell Biology and Signalling, Division of Molecular Biology, Ruđer Bošković Institute, 10000 Zagreb, Croatia; (I.S.); (M.P.); (N.S.)
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Villa-Diaz LG, Kim JK, Laperle A, Palecek SP, Krebsbach PH. Inhibition of Focal Adhesion Kinase Signaling by Integrin α6β1 Supports Human Pluripotent Stem Cell Self-Renewal. Stem Cells 2016; 34:1753-64. [PMID: 26930028 DOI: 10.1002/stem.2349] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Revised: 01/14/2016] [Accepted: 02/01/2016] [Indexed: 12/22/2022]
Abstract
Self-renewal of human embryonic stem cells and human induced pluripotent stem cells (hiPSCs)-known as pluripotent stem cells (PSC)-is influenced by culture conditions, including the substrate on which they are grown. However, details of the molecular mechanisms interconnecting the substrate and self-renewal of these cells remain unclear. We describe a signaling pathway in hPSCs linking self-renewal and expression of pluripotency transcription factors to integrin α6β1 and inactivation of focal adhesion kinase (FAK). Disruption of this pathway results in hPSC differentiation. In hPSCs, α6β1 is the dominant integrin and FAK is not phosphorylated at Y397, and thus, it is inactive. During differentiation, integrin α6 levels diminish and Y397 FAK is phosphorylated and activated. During reprogramming of fibroblasts into iPSCs, integrin α6 is upregulated and FAK is inactivated. Knockdown of integrin α6 and activation of β1 integrin lead to FAK phosphorylation and reduction of Nanog, Oct4, and Sox2, suggesting that integrin α6 functions in inactivation of integrin β1 and FAK signaling and prevention of hPSC differentiation. The N-terminal domain of FAK, where Y397 is localized, is in the nuclei of hPSCs interacting with Oct4 and Sox2, and this immunolocalization is regulated by Oct4. hPSCs remodel the extracellular microenvironment and deposit laminin α5, the primary ligand of integrin α6β1. Knockdown of laminin α5 resulted in reduction of integrin α6 expression, phosphorylation of FAK and decreased Oct4. In conclusion, hPSCs promote the expression of integrin α6β1, and nuclear localization and inactivation of FAK to supports stem cell self-renewal. Stem Cells 2016;34:1753-1764.
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Affiliation(s)
- Luis G Villa-Diaz
- Department of Biologic & Materials Sciences, University of Michigan School of Dentistry, Ann Arbor, Michigan, USA
| | - Jin Koo Kim
- Department of Biologic & Materials Sciences, University of Michigan School of Dentistry, Ann Arbor, Michigan, USA
| | - Alex Laperle
- Department of Biomedical Engineering, University of Michigan School of Dentistry, Ann Arbor, Michigan, USA
| | - Sean P Palecek
- Department of Chemical & Biological Engineering, University of Wisconsin, Madison, Wisconsin, USA
| | - Paul H Krebsbach
- Department of Biologic & Materials Sciences, University of Michigan School of Dentistry, Ann Arbor, Michigan, USA.,Biointerfaces Institute, University of Michigan, Ann Arbor, Michigan, USA
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Subbaram S, Lyons SP, Svenson KB, Hammond SL, McCabe LG, Chittur SV, DiPersio CM. Integrin α3β1 controls mRNA splicing that determines Cox-2 mRNA stability in breast cancer cells. J Cell Sci 2014; 127:1179-89. [PMID: 24434582 DOI: 10.1242/jcs.131227] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
It is unknown how cues from the tumor microenvironment can regulate post-transcriptional mechanisms, such as alternative splicing, that control genes that drive malignant growth. The induction of cyclooxygenase 2 (Cox-2) by integrin α3β1 in breast cancer cells can promote tumor progression. We have used RNAi to suppress α3β1 in human MDA-MB-231 breast cancer cells and then investigated changes in global gene expression. Numerous mRNAs, including Cox-2, show altered expression and/or alternative exon usage (AEU) in α3β1-deficient cells. AEU included patterns predicted to render an mRNA susceptible to degradation, such as 3'-UTR variations or retention of elements that target an mRNA for nonsense-mediated decay (NMD). PCR-based analysis of α3β1-deficient cells confirmed changes in Cox-2 mRNA that might target it for NMD, including retention of an intron that harbors premature termination codons and changes within the 3'-UTR. Moreover, Cox-2 mRNA has reduced stability in α3β1-deficient cells, which is partially reversed by knockdown of the essential NMD factor UPF1. Our study identifies α3β1-mediated AEU as a novel paradigm of integrin-dependent gene regulation that has potential for exploitation as a therapeutic target.
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Affiliation(s)
- Sita Subbaram
- Center for Cell Biology and Cancer Research, Albany Medical College, MC-165, 47 New Scotland Avenue, Albany, NY 12208, USA
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Ghavampour S, Lange C, Bottino C, Gerke V. Transcriptional profiling of human monocytes identifies the inhibitory receptor CD300a as regulator of transendothelial migration. PLoS One 2013; 8:e73981. [PMID: 24058511 PMCID: PMC3776808 DOI: 10.1371/journal.pone.0073981] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2012] [Accepted: 07/31/2013] [Indexed: 01/13/2023] Open
Abstract
Local inflammatory responses are characterized by the recruitment of circulating leukocytes from the blood to sites of inflammation, a process requiring the directed migration of leukocytes across the vessel wall and hence a penetration of the endothelial lining. To identify underlying signalling events and novel factors involved in these processes we screened for genes differentially expressed in human monocytes following their adhesion to and passage through an endothelial monolayer. Functional annotation clustering of the genes identified revealed an overrepresentation of those associated with inflammation/immune response, in particular early monocyte to macrophage differentiation. Among the gene products so far not implicated in monocyte transendothelial migration was the inhibitory immune receptor CD300a. CD300a mRNA and protein levels were upregulated following transmigration and engagement of the receptor by anti-CD300a antibodies markedly reduced monocyte transendothelial migration. In contrast, siRNA mediated downregulation of CD300a in human monocytes increased their rate of migration. CD300a colocalized and cosedimented with actin filaments and, when activated, caused F-actin cytoskeleton alterations. Thus, monocyte transendothelial migration is accompanied by an elevation of CD300a which serves an inhibitory function possibly required for termination of the actual transmigration.
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Affiliation(s)
- Sharang Ghavampour
- Center for Molecular Biology of Inflammation, Institute of Medical Biochemistry, Muenster, Germany
| | - Carsten Lange
- Center for Molecular Biology of Inflammation, Institute of Medical Biochemistry, Muenster, Germany
| | - Cristina Bottino
- Dipartimento di Medicina Sperimentale, Sezione di Patologia Generale, Laboratorio di Immunologia Clinica e Sperimentale, Instituto Giannina Gaslini, Genova, Italy
| | - Volker Gerke
- Center for Molecular Biology of Inflammation, Institute of Medical Biochemistry, Muenster, Germany
- * E-mail:
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Walker TN, Cimakasky LM, Coleman EM, Madison MN, Hildreth JE. Antibody against integrin lymphocyte function-associated antigen 1 inhibits HIV type 1 infection in primary cells through caspase-8-mediated apoptosis. AIDS Res Hum Retroviruses 2013; 29:371-83. [PMID: 22697794 DOI: 10.1089/aid.2011.0395] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
HIV-1 infection induces formation of a virological synapse wherein CD4, chemokine receptors, and cell-adhesion molecules such as lymphocyte function-associated antigen 1 (LFA-1) form localized domains on the cell surface. Studies show that LFA-1 on the surface of HIV-1 particles retains its adhesion function and enhances virus attachment to susceptible cells by binding its counterreceptor intercellular adhesion molecule 1 (ICAM-1). This virus-cell interaction augments virus infectivity by facilitating binding and entry events. In this study, we demonstrate that inhibition of the LFA-1/ICAM-1 interaction by a monoclonal antibody leads to decreased virus production and spread in association with increased apoptosis of HIV-infected primary T cells. The data indicate that the LFA-1/ICAM-1 interaction may limit apoptosis in HIV-1-infected T cells. This phenomenon appears similar to anoikis wherein epithelial cells are protected from apoptosis conferred by ligand-bound integrins. These results have implications for further understanding HIV pathogenesis and replication in peripheral compartments and lymphoid organs.
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Affiliation(s)
- Tiffany N. Walker
- Center for AIDS Health Disparities Research, Meharry Medical College, Nashville, Tennessee
| | | | - Ebony M. Coleman
- Department of Molecular and Cellular Biology, College of Biological Sciences, University of California, Davis, Davis, California
| | - M. Nia Madison
- Center for AIDS Health Disparities Research, Meharry Medical College, Nashville, Tennessee
| | - James E.K. Hildreth
- Department of Molecular and Cellular Biology, College of Biological Sciences, University of California, Davis, Davis, California
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Takeuchi T, Tsuzaka K, Abe T, Yoshimoto K, Shiraishi K, Kameda H, Amano K. T cell abnormalities in systemic lupus erythematosus. Autoimmunity 2009; 38:339-46. [PMID: 16227148 DOI: 10.1080/08916930500123983] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Because of the consensus that T cells play a central role in the pathogenesis of systemic lupus erythematosus (SLE), we explored the molecular basis of the defective function of SLE T cells for expression of signal transduction molecules, as well as surface structures such as adhesion molecules, by extensively testing peripheral blood T cells from SLE patients. Upregulated expression and function of adhesion molecules was observed in T cells from patients with active SLE who had specific clinical manifestations such as vasculitis, epithelitis and arthritis, but proximal signal transduction was defective. Comprehensive analysis to identify the molecules responsible for the defects showed the expression of the TCR zeta chain was attenuated, or absent in more than half of SLE patients. Moreover, the aberrant transcripts of the TCR zeta chain, including spliced variants lacking exon 7 and with a short 3' UTR, were detected in SLE T cells. Although attenuated expression of the TCR zeta chain is also observed in patients with cancers, infections and other autoimmune diseases, sustained attenuation of TCR zeta expression and aberrant transcripts are only observed in SLE. In this review we discuss the unique features of the TCR zeta defects in SLE.
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Jiang JX, Mikami K, Venugopal S, Li Y, Török NJ. Apoptotic body engulfment by hepatic stellate cells promotes their survival by the JAK/STAT and Akt/NF-kappaB-dependent pathways. J Hepatol 2009; 51:139-48. [PMID: 19457567 PMCID: PMC2765371 DOI: 10.1016/j.jhep.2009.03.024] [Citation(s) in RCA: 121] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2008] [Revised: 02/20/2009] [Accepted: 03/02/2009] [Indexed: 02/07/2023]
Abstract
BACKGROUND/AIMS We have previously shown that phagocytosis of apoptotic bodies (AB) by hepatic stellate cells (HSC) is profibrogenic. As HSC survival is central to the progression of liver fibrosis, our goal was to investigate if phagocytosis induces HSC survival. METHODS Apoptosis of phagocytosing HSC was studied in the presence of known apoptotic agents. The JAK/STAT- and PI3K/Akt-dependent pathways, NF-kappaB activation and expression of the anti-apoptotic proteins Mcl-1 and A1 were evaluated. Apoptosis was assessed after blocking A1 by an siRNA approach. RESULTS Phagocytosing HSC were resistant to FasL/cycloheximide or TRAIL-induced apoptosis. Inhibition of the JAK/STAT or PI3K-mediated pathways induced apoptosis of HSC. Phagocytosis induced JAK1/STAT3 phosphorylation, and this was prevented by inhibiting JAK. Translocation of STAT3 to the nucleus was also blocked by JAK inhibition. Mcl-1 expression was upregulated in a JAK-dependent manner. PI3K-dependent phosphorylation of Akt depended on NADPH oxidase activity and superoxide production. NF-kappaB activation and subsequent upregulation of A1 was observed, and A1 inhibition induced apoptosis of HSC. CONCLUSION Phagocytosis of AB promotes HSC survival by two pathways, of which the A1 dependent is more significant. This represents a new mechanism by which engulfment of AB contributes to the propagation of liver fibrosis.
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Affiliation(s)
- Joy X. Jiang
- Department of Internal Medicine, Division of Gastroenterology and Hepatology, UC Davis Medical Center, Sacramento, CA, USA
| | - Kenichiro Mikami
- Department of Internal Medicine, Division of Gastroenterology and Hepatology, UC Davis Medical Center, Sacramento, CA, USA
| | - Senthil Venugopal
- Department of Internal Medicine, Division of Transplant Medicine, UC Davis Medical Center, Sacramento, CA, USA
| | - Yong Li
- Department of Internal Medicine, Division of Gastroenterology and Hepatology, UC Davis Medical Center, Sacramento, CA, USA
| | - Natalie J Török
- Department of Internal Medicine, Division of Gastroenterology and Hepatology, UC Davis Medical Center, Sacramento, CA, USA
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8
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Su CC, Lin YP, Cheng YJ, Huang JY, Chuang WJ, Shan YS, Yang BC. Phosphatidylinositol 3-Kinase/Akt Activation by Integrin-Tumor Matrix Interaction Suppresses Fas-Mediated Apoptosis in T Cells. THE JOURNAL OF IMMUNOLOGY 2007; 179:4589-97. [PMID: 17878356 DOI: 10.4049/jimmunol.179.7.4589] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
It has recently become apparent that the microenvironment made up of the extracellular matrix may affect cell signaling. In this study, we evaluated Fas-triggered apoptosis in T cells in contact with tumor cells, which resembles the cell-to-cell interactions found in tumor regions. Jurkat cells were less susceptible to the Fas-mediated apoptosis when cocultured with U118, HeLa, A549, and Huh-7 tumor cells. This was indicated by less plasma membrane alteration, an amelioration of the loss of mitochondria membrane potential, a decrease in caspase-8 and caspase-3 activation, a decrease in DNA fragmentation factor-45/35 cleavage, and a reduction in the breakage of DNA when compared with Jurkat cells cultured alone. In contrast, the tumor cell lines MCF-7 and HepG2 produced no such protective effect. This protective event was independent of the expression of Fas ligand on the tumor cells. Interrupting the beta integrins-matrix interaction diminished the coculture effect. In Jurkat cells, cell matrix contact reduced the assembly of the Fas death-inducing signaling complex and Bcl-x(L) cleavage, but enhanced the phosphorylation of ERK1/2, p38 MAPK, and Akt. Only PI3K inhibitor, but not kinase inhibitors for MEK, ERK1/2, p38 MAPK, JNK, protein kinase C, and protein kinase A, completely abolished this tumor cell contact-associated protection and in parallel restored Fas-induced Bcl-x(L) cleavage as well as decreasing the phosphorylation of Bad at serine 136. Together, our results indicate that stimulation of the beta integrin signal of T cells by contact with tumor cells may trigger a novel protective signaling through the PI3K/Akt pathway of T cells against Fas-mediated apoptosis.
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Affiliation(s)
- Chung-Chen Su
- Institute of Basic Medical Sciences, National Cheng Kung University, Tainan, Taiwan, Republic of China
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9
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Smith MS, Bivins-Smith ER, Tilley AM, Bentz GL, Chan G, Minard J, Yurochko AD. Roles of phosphatidylinositol 3-kinase and NF-kappaB in human cytomegalovirus-mediated monocyte diapedesis and adhesion: strategy for viral persistence. J Virol 2007; 81:7683-94. [PMID: 17507481 PMCID: PMC1933358 DOI: 10.1128/jvi.02839-06] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Infected peripheral blood monocytes are proposed to play a key role in the hematogenous dissemination of human cytomegalovirus (HCMV) to tissues, a critical step in the establishment of HCMV persistence and the development of HCMV-associated diseases. We recently provided evidence for a unique strategy involved in viral dissemination: HCMV infection of primary human monocytes promotes their transendothelial migration and differentiation into proinflammatory macrophages permissive for the replication of the original input virus. To decipher the mechanism of hematogenous spread, we focused on the viral dysregulation of early cellular processes involved in transendothelial migration. Here, we present evidence that both phosphatidylinositol 3-kinase [PI(3)K] and NF-kappaB activities were crucial for the HCMV induction of monocyte motility and firm adhesion to endothelial cells. We found that the beta(1) integrins, the beta(2) integrins, intracellular adhesion molecule 1 (ICAM-1), and ICAM-3 were upregulated following HCMV infection and that they played a key role in the firm adhesion of infected monocytes to the endothelium. The viral regulation of adhesion molecule expression is complex, with PI(3)K and NF-kappaB affecting the expression of each adhesion molecule at different stages of the expression cascade. Our data demonstrate key roles for PI(3)K and NF-kappaB signaling in the HCMV-induced cellular changes in monocytes and identify the biological rationale for the activation of these pathways in infected monocytes, which together suggest a mechanism for how HCMV promotes viral spread to and persistence within host organs.
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Affiliation(s)
- M Shane Smith
- Department of Microbiology and Immunology, Louisiana State University Health Sciences Center, 1501 Kings Highway, Shreveport, LA 71130-3932, USA
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10
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Bozzo C, Sabbatini M, Tiberio R, Piffanelli V, Santoro C, Cannas M. Activation of caspase-8 triggers anoikis in human neuroblastoma cells. Neurosci Res 2006; 56:145-53. [PMID: 16872704 DOI: 10.1016/j.neures.2006.06.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2005] [Revised: 05/31/2006] [Accepted: 06/19/2006] [Indexed: 01/23/2023]
Abstract
Cells require appropriate interaction with extracellular matrix proteins mediated by integrins to grow, differentiate and survive. Many cell types including nervous cells undergo anoikis, a substrate-dependent apoptosis, when adhesion is impaired. Resistance of tumors to cytotoxic drugs is probably due to disturbed apoptosis programs. The proteolytic enzymes caspases are the main executioners of apoptosis. It was reported that caspase-8 expression is deficient in some neuroblastoma cells. We demonstrated that human neuroblastoma cell line SK-B-BE, differentiated with retinoic acid, expressed caspases 3, 8 and 9. Caspases 8 and 3, but not caspase-9 were activated in SK-N-BE cells cultured in suspension or on aspecific adhesive substrate. Cell positive to caspase-8 were classified into four stages, by morphometric and densitometric parameters. The use of the specific caspase-8 inhibitor Z-IETD-FMK dramatically reduced apoptosis, demonstrating that caspase-8 is the upstream initiator caspase during SK-N-BE cells anoikis. Among matrix proteins, type I collagen is the most effective and fibronectin the least in delaying anoikis. The activation of caspases 8 and 3 by unligated integrins was dependent on the state of neuronal differentiation, since the most differentiated cell was the most vulnerable to anoikis. These data show that activation of caspase-8 is specifically required to promote anoikis in SK-N-BE neuroblastoma cells.
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Affiliation(s)
- Chiarella Bozzo
- Department of Clinical and Experimental Medicine, University of Eastern Piedmont A. Avogadro, Novara, Italy.
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Molteni R, Fabbri M, Bender JR, Pardi R. Pathophysiology of leukocyte-tissue interactions. Curr Opin Cell Biol 2006; 18:491-8. [PMID: 16904306 DOI: 10.1016/j.ceb.2006.08.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2006] [Accepted: 08/01/2006] [Indexed: 10/25/2022]
Abstract
Unlike most somatic cells, leukocytes are constitutively non-adherent. However, adhesive interactions are not only a required step in essentially all effector functions performed by leukocytes, but they also relay increasingly well-defined intracellular signals that affect the leukocyte as well as the surrounding tissues. Dissecting such signals in leukocytes has provided a wealth of information that contributes to our understanding of how adhesion controls higher-order biological responses, ranging from cell migration to proliferation, differentiation and survival.
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Affiliation(s)
- Raffaella Molteni
- Unit of Leukocyte Biology, Vita-Salute San Raffaele University School of Medicine, DIBIT-Scientific Institute San Raffaele, Milano, Italy
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Abstract
Rho family GTPases are key signal transducers that regulate cell adhesion and migration and a variety of other cellular responses, including changes in gene expression. In this review, we discuss how Rho GTPases regulate signaling by endothelial cell receptors involved in leukocyte extravasation. First, Rho GTPases affect the expression of some leukocyte adhesion molecules on endothelial cells, such as intracellular adhesion molecule-1 and E-selectin, that can be induced by proinflammatory mediators, hypoxia, or shear stress. Second, Rho GTPases are activated by engagement of several leukocyte adhesion receptors and contribute to both early morphological changes and subsequent alterations in gene expression. Rho GTPases are therefore candidate targets for inhibiting leukocyte transendothelial migration in heart disease and chronic inflammatory disorders.
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Affiliation(s)
- Eva Cernuda-Morollón
- Ludwig Institute for Cancer Research, Royal Free and University College School of Medicine, London, UK
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13
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Ross EA, Douglas MR, Wong SH, Ross EJ, Curnow SJ, Nash GB, Rainger E, Scheel-Toellner D, Lord JM, Salmon M, Buckley CD. Interaction between integrin alpha9beta1 and vascular cell adhesion molecule-1 (VCAM-1) inhibits neutrophil apoptosis. Blood 2005; 107:1178-83. [PMID: 16223772 PMCID: PMC3132455 DOI: 10.1182/blood-2005-07-2692] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
According to the prevailing paradigm, neutrophils are short-lived cells that undergo spontaneous apoptosis within 24 hours of their release from the bone marrow. However, neutrophil survival can be significantly prolonged within inflamed tissue by cytokines, inflammatory mediators, and hypoxia. During screening experiments aimed at identifying the effect of the adhesive microenvironment on neutrophil survival, we found that VCAM-1 (CD106) was able to delay both spontaneous and Fas-induced apoptosis. VCAM-1-mediated survival was as efficient as that induced by the cytokine IFN-beta and provided an additive, increased delay in apoptosis when given in combination with IFN-beta. VCAM-1 delivered its antiapoptotic effect through binding the integrin alpha9beta1. The alpha9beta1 signaling pathway shares significant features with the IFN-beta survival signaling pathway, requiring PI3 kinase, NF-kappaB activation, as well as de novo protein synthesis, but the kinetics of NF-kappaB activation by VCAM-1 were slower and more sustained compared with IFN-beta. This study demonstrates a novel functional role for alpha9beta1 in neutrophil biology and suggests that adhesive signaling pathways provide an important extrinsic checkpoint for the resolution of inflammatory responses in tissues.
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Affiliation(s)
- Ewan A Ross
- Division of Immunity and Infection, Medical Research Council (MRC) Centre for Immune Regulation, Institute for Biomedical Research, University of Birmingham, United Kingdom
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14
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Herndon TM, Pirone DM, Tsokos GC, Chen CS. T cell-to-T cell clustering enhances NF-κB activity by a PI3K signal mediated by Cbl-b and Rho. Biochem Biophys Res Commun 2005; 332:1133-9. [PMID: 15922296 DOI: 10.1016/j.bbrc.2005.05.064] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2005] [Accepted: 05/10/2005] [Indexed: 11/25/2022]
Abstract
Full activation of T cells requires the binding of antigen to the T cell receptor and stimulation of the CD28 molecule, a process which typically occurs when T cells bind to an antigen presenting cell. The transcription factor, NF-kappaB, is an integration point for these two signals and its activation is critical for T cell function. Using antibodies to the TCR and CD28 molecules to activate Jurkat T cells, we show that cells that were permitted to aggregate into multi-cellular clusters increased NF-kappaB activity compared to unclustered cells. Inhibition of PI3K signaling with wortmannin decreased the clustering-mediated NF-kappaB signal. Over-expression of a dominant negative form of Cbl-b, an endogenous inhibitor of PI3K, in unclustered cells rescued NF-kappaB activation to the same levels caused by cell clustering. Inhibiting signaling through Rho with dominant negative RhoA abrogated both clustering-mediated and dominant negative Cbl-b-mediated NF-kappaB inactivation, but not TCR/CD28 mediated NF-kappaB activation. Taken together, these results suggest that in addition to pathways stimulated by classical T cell-APC interactions, another signal arising from T cell clustering can enhance activation.
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Affiliation(s)
- Thomas M Herndon
- Department of Biomedical Engineering, Johns Hopkins School of Medicine, Baltimore, MD 21205, USA
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15
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Nourshargh S, Marelli-Berg FM. Transmigration through venular walls: a key regulator of leukocyte phenotype and function. Trends Immunol 2005; 26:157-65. [PMID: 15745858 DOI: 10.1016/j.it.2005.01.006] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Leukocyte transmigration is a key event in host defense. As well as delivering leukocytes to sites of inflammation, this response also has an important role in immunity by regulating the responsiveness and behavior of leukocytes in the extravascular tissue. Recent evidence suggests that these events are associated with phenotypic and functional changes in migrating leukocytes mediated by signaling and transcriptional events triggered by the molecular interactions involved in leukocyte transendothelial cell migration. Transfer of membrane proteins from endothelial cells to migrating leukocytes and interaction of leukocytes with components of the perivascular basement membrane might also contribute to this effect. This Review will discuss the characteristics, potential mechanisms and the relevance of transmigration-induced change in leukocyte phenotype and responsiveness both within physiological and pathological scenarios.
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Affiliation(s)
- Sussan Nourshargh
- The Eric Bywaters Centre for Vascular Inflammation, Faculty of Medicine, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London, UK, W12 ONN.
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Goetz FW, Iliev DB, McCauley LAR, Liarte CQ, Tort LB, Planas JV, Mackenzie S. Analysis of genes isolated from lipopolysaccharide-stimulated rainbow trout (Oncorhynchus mykiss) macrophages. Mol Immunol 2005; 41:1199-210. [PMID: 15482855 DOI: 10.1016/j.molimm.2004.06.005] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2004] [Indexed: 11/24/2022]
Abstract
A primary cell culture system was used to obtain differentiated rainbow trout (Oncorhynchus mykiss) macrophages that were stimulated with Escherichia coli lipopolysaccharide (LPS-10 microg/ml) for 12 h in vitro. Messenger RNA from the LPS-stimulated cells was used to create two cDNA libraries from which a total of 1048 sequences were analyzed. A large number of cDNAs were obtained that could be related to immune function including structural proteins, proteases and antiproteases, regulators of transcription and translation, cell death regulators, receptors, lectins and immunoglobulins, cytokines and chemokines, cell surface antigens, signal transduction proteins, antimicrobial peptides, and enzymes involved in eicosanoid synthesis. Selected genes that were analyzed by RT-PCR and real time PCR and found to be upregulated by LPS, included vascular cell adhesion molecule, the CCAAT/enhancer binding protein beta, the inhibitor of NF-kB alpha, CD209, a major histocompatibility class II-invariant chain protein, cyclin L1, acute phase serum amyloid A, and prostaglandin endoperoxide synthase 2.
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Affiliation(s)
- Frederick W Goetz
- Marine Biological Laboratory, Program in Scientific Aquaculture, Woods Hole 02543, USA.
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17
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Abstract
As our understanding of integrins as multifunctional adhesion and signaling molecules has grown, so has their recognition as potential therapeutic targets in human diseases. Leukocyte integrins are of particular interest in this regard, as they are key molecules in immune-mediated and inflammatory processes and are thus critically involved in diverse clinical disorders, ranging from asthma to atherosclerosis. Antagonists that interfere with integrin-dependent leukocyte trafficking and/or post-trafficking events have shown efficacy in multiple preclinical models, but these have not always predicted success in subsequent clinical trials (e.g., ischemia-reperfusion disorders and transplantation). However, recent successes of integrin antagonists in psoriasis, inflammatory bowel disease, and multiple sclerosis demonstrate the tremendous potential of antiadhesion therapy directed at leukocyte integrins. This article will review the role of the leukocyte integrins in the inflammatory process, approaches to targeting leukocyte integrins and their ligands, and the results of completed clinical trials.
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Affiliation(s)
- Karyn Yonekawa
- Division of Nephrology, Department of Pediatrics, University of Washington, Seattle, WA, USA
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18
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Sturm A, Krivacic KA, Fiocchi C, Levine AD. Dual Function of the Extracellular Matrix: Stimulatory for Cell Cycle Progression of Naive T Cells and Antiapoptotic for Tissue-Derived Memory T Cells. THE JOURNAL OF IMMUNOLOGY 2004; 173:3889-900. [PMID: 15356137 DOI: 10.4049/jimmunol.173.6.3889] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Tissue T cells encounter Ag in a distinct microenvironment, where they are embedded in the interstitial extracellular matrix (ECM). In contrast, while naive T cells are exposed to Ag in the lymph node, immediately after naive T cells are activated they must extravasate into the ECM to function effectively. Because integrin-mediated adhesion to the ECM modulates cell cycle progression and survival in adherent nonimmune cells, we hypothesize that blood and tissue-derived T cells have similarly adapted their behavior to their first or continued encounter with ECM. T cells from peripheral blood (PBT) and tissue (the intestinal lamina propria T cell (LPT)) were stimulated with anti-CD3-coated beads in the presence or absence of native ECM derived from intestinal fibroblasts, plate-immobilized fibronectin, or collagen type I. Native ECM and collagen, but not fibronectin, induced in anti-CD3 activated PBT a 4- to 5-fold increase in the entry, progression, and completion of the cell cycle over that triggered by anti-CD3 alone. Neutralizing beta1 integrin Abs abrogated this increase. None of these ECM proteins stimulated cell cycle progression in LPT. In contrast, anti-CD3 activation of LPT in the presence of native ECM and fibronectin reduced activation-induced cell death by 40%. These results demonstrate that naive and effector/memory T cells respond differently upon exposure to specific ECM components. When naive PBT encounter Ag in the context of ECM, their progression through the cell cycle is enhanced, favoring clonal expansion; while tissue T cell longevity may be mediated by interactions with the ECM.
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Affiliation(s)
- Andreas Sturm
- Department of Medicine, University Hospitals of Cleveland, Case Western Reserve University School of Medicine, OH 44106, USA
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19
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Abstract
Macrophages and neutrophils are the professional phagocytes of the innate immune system. Once in the inflammatory joint or the vasculitic lesion, macrophages and neutrophils contribute to the pathology observed. This article examines the mechanisms by which phagocytes contribute to the pathogenesis of these diseases.
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Affiliation(s)
- Hongtao Liu
- Division of Rheumatology, Department of Medicine, Northwestern University, Feinberg School of Medicine, 303 East Chicago Avenue, Ward 3-315, Chicago, IL 60611, USA
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20
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Shibuya K, Shirakawa J, Kameyama T, Honda SI, Tahara-Hanaoka S, Miyamoto A, Onodera M, Sumida T, Nakauchi H, Miyoshi H, Shibuya A. CD226 (DNAM-1) is involved in lymphocyte function-associated antigen 1 costimulatory signal for naive T cell differentiation and proliferation. ACTA ACUST UNITED AC 2004; 198:1829-39. [PMID: 14676297 PMCID: PMC2194159 DOI: 10.1084/jem.20030958] [Citation(s) in RCA: 196] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Upon antigen recognition by the T cell receptor, lymphocyte function–associated antigen 1 (LFA-1) physically associates with the leukocyte adhesion molecule CD226 (DNAM-1) and the protein tyrosine kinase Fyn. We show that lentiviral vector-mediated mutant (Y-F322) CD226 transferred into naive CD4+ helper T cells (Ths) inhibited interleukin (IL)-12–independent Th1 development initiated by CD3 and LFA-1 ligations. Moreover, proliferation induced by LFA-1 costimulatory signal was suppressed in mutant (Y-F322) CD226-transduced naive CD4+ and CD8+ T cells in the absence of IL-2. These results suggest that CD226 is involved in LFA-1–mediated costimulatory signals for triggering naive T cell differentiation and proliferation. We also demonstrate that although LFA-1, CD226, and Fyn are polarized at the immunological synapse upon stimulation with anti-CD3 in CD4+ and CD8+ T cells, lipid rafts are polarized in CD4+, but not CD8+, T cells. Moreover, proliferation initiated by LFA-1 costimulatory signal is suppressed by lipid raft disruption in CD4+, but not CD8+, T cells, suggesting that the LFA-1 costimulatory signal is independent of lipid rafts in CD8+ T cells.
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Affiliation(s)
- Kazuko Shibuya
- Laboratory for Immune Receptor, RIKEN Research Center for Allergy and Immunology, 3-1-1 Koyadai, Ibaraki 305-0074, Japan.
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21
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Kettritz R, Choi M, Rolle S, Wellner M, Luft FC. Integrins and cytokines activate nuclear transcription factor-kappaB in human neutrophils. J Biol Chem 2003; 279:2657-65. [PMID: 14613935 DOI: 10.1074/jbc.m309778200] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Neutrophil adhesion to extracellular matrix is necessary for an effective inflammatory response. Adhesion may accelerate neutrophil activation by affecting intracellular signaling pathways. The nuclear transcription factor kappaB (NF-kappaB) controls several cellular functions, including inflammation, proliferation, and cell survival. We explored the role of adhesion in NF-kappaB activation in human neutrophils. Cells were stimulated with tumor necrosis factor-alpha (TNF-alpha), granulocyte macrophage-colony-stimulating factor (GM-CSF), interleukin-8 (IL-8), and formyl-methionyl-leucyl-phenylalanine (fMLP). All four initiated neutrophil adherence to and spreading on fibronectin. GM-CSF and IL-8 did not activate NF-kappaB in suspended neutrophils but rapidly activated NF-kappaB under adherent conditions on matrix, as shown by IkappaB kinase activity assay, IkappaBalpha degradation, electromobility shift assay, and quantitative reverse transcriptase-PCR. In contrast, TNF-alpha activated NF-kappaB both in suspended cells and adherent cells. fMLP did not activate NF-kappaB in either suspended or adherent cells. Specific beta(2) integrin blockade prevented NF-kappaB activation by GM-CSF and IL-8 on fibronectin. Co-stimulating CD18 and CD11b with activating antibodies resulted in NF-kappaB activation by GM-CSF and IL-8 in suspended cells. We inhibited actin polymerization with cytochalasin and blocked the non-receptor kinase Syk with piceatannol. Both maneuvers prevented the co-stimulatory NF-kappaB-activating signal by beta(2) integrins. Thus, in addition to beta(2) integrin ligand binding, NF-kappaB activation depended on the formation of the receptor-associated intracellular focal adhesion complex. We conclude that beta(2) integrins may provide co-stimulatory signals allowing some soluble mediators to activate the NF-kappaB pathway even when they are not capable of doing so in suspension. This effect may become important when human neutrophils leave the circulating blood and migrate through extracellular matrix during inflammation.
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Affiliation(s)
- Ralph Kettritz
- Medical Faculty of the Charité, Department of Nephrology and Hypertension, Franz Volhard Clinic, HELIOS-Klinikum-Berlin and Max Delbrück Center for Molecular Medicine, 13125 Berlin, Germany.
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22
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Wang H, Moon EY, Azouz A, Wu X, Smith A, Schneider H, Hogg N, Rudd CE. SKAP-55 regulates integrin adhesion and formation of T cell-APC conjugates. Nat Immunol 2003; 4:366-74. [PMID: 12652296 DOI: 10.1038/ni913] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2002] [Accepted: 02/21/2003] [Indexed: 11/09/2022]
Abstract
Src kinase-associated phosphoprotein of 55 kDa (SKAP-55; encoded by SCAP1) is a T cell adaptor protein of unknown function that contains a pleckstrin homology and an SH3 domain. Here we show that SKAP-55 regulates integrin-mediated adhesion and conjugate formation between T cells and antigen-presenting cells (APCs). SKAP-55 enhances adhesion to fibronectin and intercellular adhesion molecule-1 (ICAM-1), colocalizes with actin at the T cell-APC synapse and promotes the clustering of lymphocyte-associated antigen-1 (LFA-1). Enhanced conjugation is comparable to that induced by adhesion and degranulation-promoting adaptor protein (ADAP), a binding partner of SKAP-55, and is abrogated by deletion of the SKAP-55 SH3 domain. Conjugate formation is accompanied by the translocation of SKAP-55 to membrane rafts, an event that is regulated by both LFA-1 and T cell receptor ligation. Our findings identify a mechanism by which SKAP-55 modulates T cell responses to antigen.
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Affiliation(s)
- Hongyan Wang
- Department of Haematology, Division of Investigative Sciences, Faculty of Medicine, Imperial College London, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK
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23
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Abstract
Host defense against pathogenic microbes requires dramatically different responses, depending on the character of the pathogen and on the tissue under attack. Central to the immune system's ability to mobilize a response to an invading pathogen is its ability to distinguish self from nonself. The host has evolved both innate and adaptive mechanisms to respond to and eliminate pathogenic microbes. Both of these mechanisms include self-nonself discrimination. This overview describes key mechanisms used by the immune system to respond to invading microbes and identifies settings in which disturbed immune function exacerbates tissue injury.
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Affiliation(s)
- David D Chaplin
- University of Alabama at Birmingham, 845 19th Street South, BBRB 276/11, Birmingham, AL 35294-2170, USA
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Tudek B. Imidazole ring-opened DNA purines and their biological significance. JOURNAL OF BIOCHEMISTRY AND MOLECULAR BIOLOGY 2003; 36:12-9. [PMID: 12542970 DOI: 10.5483/bmbrep.2003.36.1.012] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Fragmentation of purine imidazole ring and production of formamidopyrimidines in deoxynucleosides (Fapy lesions) occurs upon DNA oxidation as well as upon spontaneous or alkali-triggered rearrangement of certain alkylated bases. Many chemotherapeutic agents such as cyclophosphamide or thiotepa produce such lesions in DNA. Unsubstituted FapyA and FapyG, formed upon DNA oxidation cause moderate inhibition of DNA synthesis, which is DNA polymerase and sequence dependent. Fapy-7MeG, a methylated counterpart of FapyG-, a efficiently inhibits DNA replication in vitro and in E.coli, however its mutagenic potency is low. This is probably due to preferential incorporation of cytosine opposite Fapy-7MeG and preferential extension of Fapy-7MeG:C pair. In contrast, FapyA and Fapy-7MeA possess miscoding potential. Both lesions in SOS induced E.coli preferentially mispair with cytosine giving rise to A-->G transitions. Fapy lesions substituted with longer chain alkyl groups also show simult aneous lethal and mutagenic properties. Fapy lesions are actively eliminated from DNA by repair glycosylases specific for oxidized purines and pyrimidines both in bacteria and eukaryotic cells. Bacterial enzymes include E.coli formamidopyrimidine-DNA-glycosylase (Fpg protein), endonuclease III (Nth protein) and endonuclease VIII (Nei protein).
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Affiliation(s)
- Barbara Tudek
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 02-106 Warsaw, Poland.
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25
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Godschalk RWL, Van Schooten FJ, Bartsch H. A critical evaluation of DNA adducts as biological markers for human exposure to polycyclic aromatic compounds. JOURNAL OF BIOCHEMISTRY AND MOLECULAR BIOLOGY 2003; 36:1-11. [PMID: 12542969 DOI: 10.5483/bmbrep.2003.36.1.001] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The causative role of polycyclic aromatic hydrocarbons (PAH) in human carcinogenesis is undisputed. Measurements of PAH-DNA adduct levels in easily accessible white blood cells therefore represent useful early endpoints in exposure intervention or chemoprevention studies. The successful applicability of DNA adducts as early endpoints depends on several criteria: i. adduct levels in easily accessible surrogate tissues should reflect adduct levels in target-tissues, ii. toxicokinetics and the temporal relevance should be properly defined. iii. sources of interand intra-individual variability must be known and controllable, and finally iv. adduct analyses must have advantages as compared to other markers of PAHexposure. In general, higher DNA adduct levels or a higher proportion of subjects with detectable DNA adduct levels were found in exposed individuals as compared with nonexposed subjects, but saturation may occur at high exposures. Furthermore, DNA adduct levels varied according to changes in exposure, for example smoking cessation resulted in lower DNA adduct levels and adduct levels paralleled seasonal variations of air-pollution. Intraindividual variation during continuous exposure was low over a short period of time (weeks), but varied significantly when longer time periods (months) were investigated. Inter-individual variation is currently only partly explained by genetic polymorphisms in genes involved in PAH-metabolism and deserves further investigation. DNA adduct measurements may have three advantages over traditional exposure assessment: i. they can smooth the extreme variability in exposure which is typical for environmental toxicants and may integrate exposure over a longer period of time. Therefore, DNA adduct assessment may reduce the monitoring effort. ii. biological monitoring of DNA adducts accounts for all exposure routes. iii. DNA adducts may account for inter-individual differences in uptake, elimination, distribution, metabolism and repair amongst exposed individuals. In conclusion, there is now a sufficiently large scientific basis to justify the application of DNA adduct measurements as biomarkers in exposure assessment and intervention studies. Their use in risk-assessment, however, requires further investigation.
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Affiliation(s)
- Roger W L Godschalk
- Department of Health Risk Analysis and Toxicology, University of Maastricht, 6200 MD Maastricht, The Netherlands.
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26
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Choi KS, Bae MK, Jeong JW, Moon HE, Kim KW. Hypoxia-induced angiogenesis during carcinogenesis. JOURNAL OF BIOCHEMISTRY AND MOLECULAR BIOLOGY 2003; 36:120-7. [PMID: 12542982 DOI: 10.5483/bmbrep.2003.36.1.120] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The formation of new blood vessels, angiogenesis, is an essential process during development and disease. Angiogenesis is well known as a crucial step in tumor growth and progression. Angiogenesis is induced by hypoxic conditions and regulated by the hypoxia-inducible factor 1 (HIF-1). The expression of HIF-1 correlates with hypoxia-induced angiogenesis as a result of the induction of the major HIF-1 target gene, vascular endothelial cell growth factor (VEGF). In this review, a brief overview of the mechanism of angiogenesis is discussed, focusing on the regulatory processes of the HIF-1 transcription factor. HIF-1 consists of a constitutively expressed HIF-1 beta (HIF-1beta) subunit and an oxygen-regulated HIF-1 alpha (HIF-1a) subunit. The stability and activity of HIF-1alpha are regulated by the interaction with various proteins, such as pVHL, p53, and p300/CBP as well as by post-translational modifications, hydroxylation, acetylation, and phosphorylation. It was recently reported that HIF-1alpha binds a co-activator of the AP-1 transcription factor, Jab-1, which inhibits the p53-dependent degradation of HIF-1 and enhances the transcriptional activity of HIF-1 and the subsequent VEGF expression under hypoxic conditions. ARD1 acetylates HIF-1alpha and stimulates pVHL-mediated ubiquitination of HIF-1alpha. With a growing knowledge of the molecular mechanisms in this field, novel strategies to prevent tumor angiogenesis can be developed, and from these, new anticancer therapies may arise.
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Affiliation(s)
- Kyu-Sil Choi
- Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Seoul 151-742, Korea
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