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The hidden side of SERPINB1/Leukocyte Elastase Inhibitor. Semin Cell Dev Biol 2016; 62:178-186. [PMID: 27422329 DOI: 10.1016/j.semcdb.2016.07.010] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Revised: 06/13/2016] [Accepted: 07/08/2016] [Indexed: 12/20/2022]
Abstract
SERPINB1, also called Leukocyte Elastase Inhibitor (LEI) is a member of the clade B of SERPINS. It is an intracellular protein and acts primarily to protect the cell from proteases released into the cytoplasm during stress. Its role in inflammation is clear due to its involvement in the resolution of chronic inflammatory lung and bowel diseases. LEI/SERPINB1 intrinsically possesses two enzymatic activities: an antiprotease activity dependent on its reactive site loop, which is analogous to the other proteins of the family and an endonuclease activity which is unveiled by the cleavage of the reactive site loop. The conformational change induced by this cleavage also unveils a bipartite nuclear localization signal allowing the protein to translocate to the nucleus. Recent data indicate that it has also a role in cell migration suggesting that it could be involved in diverse processes like wound healing and malignant metastases.
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2
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Lebon C, Rodriguez GV, Zaoui IE, Jaadane I, Behar-Cohen F, Torriglia A. On the use of an appropriate TdT-mediated dUTP-biotin nick end labeling assay to identify apoptotic cells. Anal Biochem 2015; 480:37-41. [PMID: 25862087 DOI: 10.1016/j.ab.2015.04.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Revised: 04/01/2015] [Accepted: 04/03/2015] [Indexed: 12/12/2022]
Abstract
Apoptosis is an essential cellular mechanism involved in many processes such as embryogenesis, metamorphosis, and tissue homeostasis. DNA fragmentation is one of the key markers of this form of cell death. DNA fragmentation is executed by endogenous endonucleases such as caspase-activated DNase (CAD) in caspase-dependent apoptosis. The TUNEL (TdT-mediated dUTP-biotin nick end labeling) technique is the most widely used method to identify apoptotic cells in a tissue or culture and to assess drug toxicity. It is based on the detection of 3'-OH termini that are labeled with dUTP by the terminal deoxynucleotidyl transferase. Although the test is very reliable and sensitive in caspase-dependent apoptosis, it is completely useless when cell death is mediated by pathways involving DNA degradation that generates 3'-P ends as in the LEI/L-DNase II pathway. Here, we propose a modification in the TUNEL protocol consisting of a dephosphorylation step prior to the TUNEL labeling. This allows the detection of both types of DNA breaks induced during apoptosis caspase-dependent and independent pathways, avoiding underestimating the cell death induced by the treatment of interest.
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Affiliation(s)
- Cecile Lebon
- Centre de Recherches des Cordeliers, INSERM U1138, Université Pierre et Marie Curie, Université Paris Descartes, 75006 Paris, France
| | - Gloria Villalpando Rodriguez
- Centre de Recherches des Cordeliers, INSERM U1138, Université Pierre et Marie Curie, Université Paris Descartes, 75006 Paris, France
| | - Ikram El Zaoui
- Centre de Recherches des Cordeliers, INSERM U1138, Université Pierre et Marie Curie, Université Paris Descartes, 75006 Paris, France
| | - Imene Jaadane
- Centre de Recherches des Cordeliers, INSERM U1138, Université Pierre et Marie Curie, Université Paris Descartes, 75006 Paris, France
| | - Francine Behar-Cohen
- Centre de Recherches des Cordeliers, INSERM U1138, Université Pierre et Marie Curie, Université Paris Descartes, 75006 Paris, France
| | - Alicia Torriglia
- Centre de Recherches des Cordeliers, INSERM U1138, Université Pierre et Marie Curie, Université Paris Descartes, 75006 Paris, France.
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3
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Wride MA. Lens fibre cell differentiation and organelle loss: many paths lead to clarity. Philos Trans R Soc Lond B Biol Sci 2011; 366:1219-33. [PMID: 21402582 DOI: 10.1098/rstb.2010.0324] [Citation(s) in RCA: 152] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The programmed removal of organelles from differentiating lens fibre cells contributes towards lens transparency through formation of an organelle-free zone (OFZ). Disruptions in OFZ formation are accompanied by the persistence of organelles in lens fibre cells and can contribute towards cataract. A great deal of work has gone into elucidating the nature of the mechanisms and signalling pathways involved. It is apparent that multiple, parallel and redundant pathways are involved in this process and that these pathways form interacting networks. Furthermore, it is possible that the pathways can functionally compensate for each other, for example in mouse knockout studies. This makes sense given the importance of lens clarity in an evolutionary context. Apoptosis signalling and proteolytic pathways have been implicated in both lens fibre cell differentiation and organelle loss, including the Bcl-2 and inhibitor of apoptosis families, tumour necrosis factors, p53 and its regulators (such as Mdm2) and proteolytic enzymes, including caspases, cathepsins, calpains and the ubiquitin-proteasome pathway. Ongoing approaches being used to dissect the molecular pathways involved, such as transgenics, lens-specific gene deletion and zebrafish mutants, are discussed here. Finally, some of the remaining unresolved issues and potential areas for future studies are highlighted.
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Affiliation(s)
- Michael A Wride
- Ocular Development and Neurobiology Research Group, Zoology Department, School of Natural Sciences, Trinity College Dublin, Dublin 2, Republic of Ireland.
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4
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Torriglia A, Leprêtre C, Padrón-Barthe L, Chahory S, Martin E. Molecular mechanism of L-DNase II activation and function as a molecular switch in apoptosis. Biochem Pharmacol 2008; 76:1490-502. [DOI: 10.1016/j.bcp.2008.07.039] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2008] [Revised: 07/14/2008] [Accepted: 07/15/2008] [Indexed: 01/22/2023]
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5
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Counis MF, Torriglia A. Acid DNases and their interest among apoptotic endonucleases. Biochimie 2006; 88:1851-8. [PMID: 16989934 DOI: 10.1016/j.biochi.2006.07.008] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2006] [Accepted: 07/05/2006] [Indexed: 01/11/2023]
Abstract
Apoptosis is characterized by cell shrinkage, nuclear condensation and internucleosomal DNA cleavage. Besides the central role of caspases and other proteases, cell death triggers DNA degradation so that DNases have an active role in apoptotic cell death. The best-characterized apoptotic DNase is CAD, a neutral Mg-dependent endonuclease. Its activity is regulated by its inhibitor, ICAD, which is cleaved by caspases. Other neutral DNases have been shown to cleave nuclear DNA in apoptotic conditions: endonuclease G, GADD. In cells, the cytosolic pH is maintained to 7.2, mostly due to the activity of the Na(+)/H(+) exchanger. In many apoptotic conditions, a decrease of the intracellular pH has been shown. This decrease may activate different acid DNases, mostly when pH decreases below 6.5. Three acidic DNases II are so far known: DNase II alpha, DNase II beta and L-DNase II, a DNase II, derived from the serpin LEI (Leukocyte Elastase Inhibitor). Their activation during cell death is discussed in this review.
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Affiliation(s)
- Marie-France Counis
- INSERM U 598, Centre de Recherches Biomédicales des Cordeliers, Paris, France.
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6
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Sanders EJ, Parker E. Retroviral overexpression of bcl-2 in the embryonic chick lens influences denucleation in differentiating lens fiber cells. Differentiation 2003; 71:425-33. [PMID: 12969335 DOI: 10.1046/j.1432-0436.2003.7107005.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
During the course of their differentiation, embryonic lens fibers undergo loss of their cytoplasmic organelles and nuclei. The denucleation process bears similarities to the nuclear breakdown that occurs during apoptosis. This has given rise to the hypothesis that this denucleation is analogous to apoptosis, but without the plasma membrane changes characteristic of apoptotic cell death. Previous work has shown that several members of the apoptotic cascade are active during denucleation. Here, we have overexpressed the anti-apoptotic molecule bcl-2 in developing lenses of the 8-day-old chick embryo in ovo, using the replication-competent retrovirus RCAS. We find that lenses overexpressing bcl-2 show varying degrees of distortion in comparison with untreated and negative insert controls, including a more spherical shape and disorganized fiber cells. All overexpressing lenses showed significantly higher numbers of smaller nuclei in the lens core, where denucleation begins. There was no change in cell size or pattern of proliferation. These in vivo results were confirmed in vitro using lens epithelial cell cultures, which differentiate into lentoids. The lentoids in treated cultures showed the same effect on nuclear number and size. We further found that in lenses overexpressing bcl-2 there was a reduction in the activation of caspase-9 and the cleavage of the caspase substrate DFF45, and, in the lens core, a failure of the nuclear chromatin to condense. These results provide strong support for the view that embryonic lens fiber cell denucleation is analogous to the nuclear degradation that occurs during apoptosis, and that similar control pathways are involved in both these phenomena.
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Affiliation(s)
- Esmond J Sanders
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada.
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7
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Nishimoto S, Kawane K, Watanabe-Fukunaga R, Fukuyama H, Ohsawa Y, Uchiyama Y, Hashida N, Ohguro N, Tano Y, Morimoto T, Fukuda Y, Nagata S. Nuclear cataract caused by a lack of DNA degradation in the mouse eye lens. Nature 2003; 424:1071-4. [PMID: 12944971 DOI: 10.1038/nature01895] [Citation(s) in RCA: 142] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2003] [Accepted: 07/04/2003] [Indexed: 02/03/2023]
Abstract
The eye lens is composed of fibre cells, which develop from the epithelial cells on the anterior surface of the lens. Differentiation into a lens fibre cell is accompanied by changes in cell shape, the expression of crystallins and the degradation of cellular organelles. The loss of organelles is believed to ensure the transparency of the lens, but the molecular mechanism behind this process is not known. Here we show that DLAD ('DNase II-like acid DNase', also called DNase IIbeta) is expressed in human and murine lens cells, and that mice deficient in the DLAD gene are incapable of degrading DNA during lens cell differentiation--the undigested DNA accumulates in the fibre cells. The DLAD-/- mice develop cataracts of the nucleus lentis, and their response to light on electroretinograms is severely reduced. These results indicate that DLAD is responsible for the degradation of nuclear DNA during lens cell differentiation, and that if DNA is left undigested in the lens, it causes cataracts of the nucleus lentis, blocking the light path.
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Affiliation(s)
- Sogo Nishimoto
- Department of Genetics, Osaka University Medical School, Osaka 565-0871, Japan.
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8
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Walker JL, Zhang L, Menko AS. A signaling role for the uncleaved form of alpha 6 integrin in differentiating lens fiber cells. Dev Biol 2002; 251:195-205. [PMID: 12435352 DOI: 10.1006/dbio.2002.0823] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Many alpha integrin subunits are cleaved during their processing to yield heavy and light chains, which remain associated by disulfide bonds. While uncleaved alpha integrin subunits can form functional receptors that sometimes have distinct signaling roles from their better-characterized endoproteolytically cleaved counterparts, their expression at the cell surface and their association with signaling complexes have yet to be determined in vivo. In this study, we demonstrate that, in differentiating lens fiber cells, the uncleaved form of alpha 6 integrin was expressed at the cell surface. This form of alpha 6 integrin coimmunoprecipitated with both the signaling adaptor molecule Shc and its downstream effector Grb2, suggesting that, in lens fiber cells, uncleaved alpha 6 integrin was associated with a Shc-mediated signaling complex. We show that expression of the cleaved form of alpha 6 integrin progressively decreased relative to uncleaved alpha 6 integrin as the state of lens cell differentiation increased, resulting in the predominance of uncleaved alpha 6 integrin in the lens fiber cell zones. Interestingly, we previously have shown that alpha 6 integrin is localized principally along the extensive cell-cell interfaces of these lens fiber cells, in the absence of its extracellular matrix ligand laminin. While we found that the cleaved form of alpha 6 integrin contained both high mannose and complex sugars, the uncleaved form of alpha 6 integrin contained only high mannose sugars. These properties suggest that the uncleaved form of alpha 6 integrin may have a unique role in the embryonic lens. Its high association with Shc and Grb2 in the differentiating cortical fiber cell zone indicates that alpha 6 integrin may provide a cell survival signal in the presence of the apoptotic-like processes that are initiated in this region of the embryonic lens to clear the lens cells of their organelles.
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Affiliation(s)
- Janice L Walker
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
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9
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Sanders EJ, Parker E. The role of mitochondria, cytochrome c and caspase-9 in embryonic lens fibre cell denucleation. J Anat 2002; 201:121-35. [PMID: 12220121 PMCID: PMC1570907 DOI: 10.1046/j.1469-7580.2002.00081.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
During the differentiation of secondary lens fibre cells from the lens epithelium, the fibre cells lose all of their cytoplasmic organelles as well as their nuclei. The fibre cells, containing crystallins, which confer optical clarity, then persist in the adult lens. The process of denucleation of these cells has been likened to an apoptotic event which is not followed by the plasma membrane changes that are characteristic of apoptosis. We have examined the expression and subcellular translocation of molecules of the apoptotic cascade in differentiating lens epithelial cells in culture. In this culture system, the epithelial cells differentiate into lentoids composed of lens fibre cells. We find that caspase-9, which is expressed and activated before embryonic day 12 in intact lenses, is localized in the cytosol outside mitochondria in non-differentiating cultured cells. In lentoid cells, caspase-9 migrates into mitochondria after the latter undergo a membrane permeability transition that is characteristic of apoptotic cells. At the same time, caspase-9 co-localizes with cytochrome c in the cytosol. The cytochrome c is apparently released from the mitochondria in lentoid cells after the mitochondrial membrane permeability transition and during the period of nuclear shrinkage. Also during this time, the mitochondria aggregate around the degenerating nuclei. Cytochrome c disappears rapidly, while mitochondrial breakdown occurs approximately coincident with the disappearance of the nuclei, but mitochondrial remnants persist together with cytochrome c oxidase, which is a mitochondrial marker protein. Apaf-1, another cytosolic protein of the apoptotic cascade, also migrates to the permeabilized mitochondria and also co-localizes with caspase-9 and cytochrome c in the cytosol or mitochondria of denucleating cells, thus providing evidence for the formation of an 'apoptosome' in these cells, as in apoptotic cells. At no time did we observe the translocation of molecules between cytoplasmic compartments and the nucleus in differentiating lentoid cells. We suggest that the uncoupling of nuclear and membrane apoptotic events in these cells may be due to the early permeability changes in the mitochondria, resulting in the loss of mitochondrial signalling molecules, or to the failure of molecules to migrate to the nucleus in these cells, thus failing to activate nuclear-plasma membrane signalling pathways.
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Affiliation(s)
- E J Sanders
- Department of Physiology, University of Alberta, Edmonton, Canada.
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10
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Wride MA, Parker E, Sanders EJ. Members of the bcl-2 and caspase families regulate nuclear degeneration during chick lens fibre differentiation. Dev Biol 1999; 213:142-56. [PMID: 10452852 DOI: 10.1006/dbio.1999.9375] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The optical clarity of the lens is ensured by the programmed removal of nuclei and other organelles from the lens fibre cells during development. The morphology of the degenerating nuclei is similar to that observed during apoptosis and is accompanied by DNA fragmentation. Proteins encoded by the bcl-2 proto-oncogene family are important in either promoting or inhibiting apoptosis, and caspases are involved in downstream proteolytic events. Here, the expression of bcl-2 family members (bcl-2, bax, bad, and bcl-x(s/l)) and caspases-1, -2, -3, -4, and -6 was investigated through a range of stages of chick lens development using immunocytochemistry, Western blotting, and affinity labelling for caspases using biotinylated caspase inhibitors. Using differentiating lens epithelial cell cultures, it was demonstrated that the addition to cultures of synthetic peptide inhibitors of caspases -1, -2, -4, -6, and -9 brought about a 50-70% reduction in the number of degenerating nuclei per unit area of culture, as assessed by image analysis. These effects were comparable to those seen when general inhibitors of caspases were added to cultures. On the other hand, inhibitors of caspases-3 and -8 were not effective in significantly reducing the number of TUNEL-labelled nuclei. Expression of the caspase substrates poly(ADP-ribose) polymerase (PARP) and the 45-kDa subunit of DNA fragmentation factor (DFF 45) was also observed in the developing lens. Western blots of cultures to which caspase inhibitors were added revealed alterations in the PARP cleavage pattern, but not in that of DFF. These results demonstrate a role for members of the bcl-2 family and caspases in the degeneration of lens fibre cell nuclei during chick secondary lens fibre development and support the proposal that this process has many characteristics in common with apoptosis.
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Affiliation(s)
- M A Wride
- Department of Physiology, University of Alberta, Edmonton, Alberta, T6G 2H7, Canada.
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11
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Krieser RJ, Eastman A. The cloning and expression of human deoxyribonuclease II. A possible role in apoptosis. J Biol Chem 1998; 273:30909-14. [PMID: 9812984 DOI: 10.1074/jbc.273.47.30909] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have previously implicated deoxyribonuclease II (DNase II) as an endonuclease responsible for DNA digestion during apoptosis. The full-length human cDNA has now been cloned. The cDNA contains an open reading frame of 1078 bases coding for a 40-kDa protein. This protein is 10 kDa larger than commercially supplied enzyme, which has been proteolytically cleaved at an internal aspartate residue. The gene is located at chromosome 19p13.2, and has no significant homology to other human proteins, but has >30% identity to three predicted genes in Caenorhabditis elegans. To determine whether overexpression of DNase II induces apoptosis in Chinese hamster ovary cells, the cDNA was cotransfected with a plasmid encoding green fluorescent protein. Within 24 h, a significant proportion of green fluorescent protein-positive cells contained condensed chromatin, whereas vector-only controls remained viable. Considering that DNase II is normally active only at low pH, it was surprising that transfection induced chromatin condensation. To confirm that transfection was not activating another endonuclease, cells were incubated with the caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp-(O-methyl)-fluoromethylketone; this failed to inhibit chromatin condensation induced by DNase II. These results demonstrate that DNase II acts downstream of caspase activation and that it may be activated by an as yet unknown mechanism to induce DNA digestion during apoptosis.
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Affiliation(s)
- R J Krieser
- Department of Pharmacology and Toxicology, Dartmouth Medical School, Hanover, New Hampshire 03655, USA
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12
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Jornot L, Petersen H, Junod AF. Hydrogen peroxide-induced DNA damage is independent of nuclear calcium but dependent on redox-active ions. Biochem J 1998; 335 ( Pt 1):85-94. [PMID: 9742216 PMCID: PMC1219755 DOI: 10.1042/bj3350085] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In cells undergoing oxidative stress, DNA damage may result from attack by .OH radicals produced by the Fenton reaction, and/or by nucleases activated by nuclear calcium. In the present study, the participation of these two mechanisms was investigated in HeLa cells. Nuclear-targeted aequorin was used for selectively monitoring Ca2+ concentrations within the nuclei ([Ca2+]n), in conjunction with the cell-permeant calcium chelator bis-(o-aminophenoxy)ethane-N,N,N', N'-tetraacetic acid acetoxymethyl ester (BAPTA/AM), the lipid-soluble broad-spectrum metal chelator with low affinity for Ca2+ and Mg2+ N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN), and the high-affinity iron/copper chelator 1, 10-phenanthroline (PHE). In Ca2+-containing medium, H2O2 induced extensive DNA strand breaks and an increase in [Ca2+]n that was almost identical to that observed in the cytosol ([Ca2+]c). In cells bathed in Ca2+-free/EGTA medium, in which the increases in [Ca2+]n and [Ca2+]c due to H2O2 were significantly reduced, similar levels of DNA fragmentation also occurred. In cells preloaded with BAPTA/AM or TPEN, the small increase of [Ca2+]n normally elicited by H2O2 in Ca2+-free medium was completely buffered, and DNA damage was largely prevented. On the other hand, pretreatment with PHE did not affect the calcium response in the nuclei, but completely prevented DNA strand breakage induced by H2O2. Re-addition of 100 microM CuSO4 and 100 microM FeSO4 to TPEN- and PHE-treated cells prior to H2O2 challenge reversed the effect of TPEN and PHE, whereas 1 mM was necessary to negate the effect of BAPTA/AM. The levels of DNA strand breakage observed, however, did not correlate with the amounts of 8-hydroxy 2'-deoxyguanosine (8-OHdG): H2O2 did not produce 8-OHdG, whereas PHE alone slightly increased 8-OHdG levels. CuSO4 and FeSO4 enhanced the effects of PHE, particularly in the presence of H2O2. Exposure of cells to a mixture of CuSO4/FeSO4 also resulted in a significant increase in 8-OHdG levels, which was prevented in cells preloaded with BAPTA/AM. Similar results were obtained in a cell-free system using isolated calf thymus DNA exposed to CuSO4/FeSO4, regardless of whether H2O2 was present or not. These results suggest that BAPTA/AM prevents H2O2-induced DNA damage by acting as an iron/copper chelator. These data also indicate that caution must be exercised in using Ca2+ chelating agents as evidence for a role in cellular Ca2+ levels in experimental conditions in which transition-metal-ion-mediated oxidant production is also occurring.
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Affiliation(s)
- L Jornot
- Respiratory Division, Department of Internal Medicine, University Hospital, 24 Micheli-Du-Crest, 1211 Geneva 14, Switzerland.
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13
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Dahm R, Gribbon C, Quinlan RA, Prescott AR. Changes in the nucleolar and coiled body compartments precede lamina and chromatin reorganization during fibre cell denucleation in the bovine lens. Eur J Cell Biol 1998; 75:237-46. [PMID: 9587055 DOI: 10.1016/s0171-9335(98)80118-0] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Nuclear elimination accompanies differentiation in such specialized cell types such as erthyrocytes and lens fibre cells. It also accompanies apoptosis which has suggested that similar processes could operate in both. Denucleation occurs in the lens in order to reduce light scatter and this process is often disrupted in cataract. Using the adult bovine lens as a model system, nuclear changes accompanying denucleation are described with particular emphasis on the lamina, nucleolar and coiled body compartments in lens nuclei. Nuclear shape, chromatin reorganization and chromatin breakdown were also monitored to correlate the timing of events. Rearrangement of both A- and B-type nuclear lamins occurred in parallel with chromatin condensation and preceded changes in nuclear shape. The earliest changes detected in this study occurred in the coiled body and nucleolar compartments using coilin and fibrillarin antibodies respectively, suggesting that a shutdown in transcription is an early event in denucleation. Fibrillarin redistributed from an open floret pattern to several condensed spots which gradually decreased in intensity and eventually disappeared. Coilin, however, was localized in several microfoci prior to being reorganized into fewer larger foci. Prior to chromatin condensation, coilin redistributed to the nucleolar compartment and was absent from nuclei where chromatin had begun to condense. Such nuclei were positive by TUNEL staining. In contrast to the nucleus, mitochondrial degradation in lens fibre cells was a rapid process and involved a relatively sharp transition between positive and negative fibre cells for two mitochondrial specific markers, BAP 37 and prohibitin. A link between the changes in the nuclear lamina and chromatin with the initiation of mitochondrial fragmentation was also observed. Therefore, it is possible that the signal for the initiation of denucleation could originate from the mitochondria as proposed for apoptosis. Differences between apoptosis and lens fibre cell denucleation were noted and included the timescale of nuclear changes as well as the persistence of a nuclear remnant. These studies suggest that transcriptional shutdown precedes lamina reorganization and chromatin breakdown during lens fibre cell denucleation.
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Affiliation(s)
- R Dahm
- Department of Biochemistry, Medical Sciences Institute, University of Dundee, UK
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14
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Mitamura S, Ikawa H, Mizuno N, Kaziro Y, Itoh H. Cytosolic nuclease activated by caspase-3 and inhibited by DFF-45. Biochem Biophys Res Commun 1998; 243:480-4. [PMID: 9480834 DOI: 10.1006/bbrc.1998.8122] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
To study the intracellular apoptotic signaling pathways, we have established a cell-free system, in which DNA fragmentation of the isolated mouse liver nuclei was induced with lysates from the Fas-activated cells. We have found that the inactive nuclease present in the intact cell cytosol is activated by a caspase-3-like protease and the activated nuclease induces the nucleosomal DNA fragmentation. We attempted the purification of the inactive nuclease from bovine liver cytosol. The partially purified nuclease was activated by recombinant caspase-3, and to a lesser extent by caspase-6. The activated nuclease was able to digest plasmid DNA in addition to induce the DNA fragmentation of nuclei. DFF-45, which is a subunit of heterodimeric protein leading to DNA fragmentation upon its digestion by caspase-3, is found to inhibit the activity of the activated nuclease. These results suggest that the inactive nuclease in cytoplasm is converted to the active form by caspases, and the activated nuclease enters into nucleus to induce the DNA fragmentation. It is suggested that DFF-45 may function as an inhibitory factor of the caspase-sensitive nuclease in vivo.
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Affiliation(s)
- S Mitamura
- Faculty of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama, Japan
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15
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Gong X, Li E, Klier G, Huang Q, Wu Y, Lei H, Kumar NM, Horwitz J, Gilula NB. Disruption of alpha3 connexin gene leads to proteolysis and cataractogenesis in mice. Cell 1997; 91:833-43. [PMID: 9413992 DOI: 10.1016/s0092-8674(00)80471-7] [Citation(s) in RCA: 285] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Gap junction channels formed by alpha3 (Cx46) and alpha8 (Cx50) connexin provide pathways for communication between the fiber cells in the normal transparent lens. To determine the specific role of alpha3 connexin in vivo, the alpha3 connexin gene was disrupted in mice. Although the absence of alpha3 connexin had no obvious influence on the early stages of lens formation and the differentiation of lens fibers, mice homozygous for the disrupted alpha3 gene developed nuclear cataracts that were associated with the proteolysis of crystallins. This study establishes the importance of gap junctions in maintaining normal lens transparency by providing a cell-cell signaling pathway or structural component for the proper organization of lens membrane and cytoplasmic proteins.
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Affiliation(s)
- X Gong
- Department of Cell Biology, The Scripps Research Institute, La Jolla, California 92037, USA
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16
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Gagna CE, Lambert WC, Kuo HR, Farnsworth PN. Localization of B-DNA and Z-DNA in terminally differentiating fiber cells in the adult lens. J Histochem Cytochem 1997; 45:1511-21. [PMID: 9358853 DOI: 10.1177/002215549704501108] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
We examined histochemically and immunohistochemically the distribution of B- and Z-DNA in the epithelium and terminally differentiating dog lens fiber cells. On the basis of anti-DNA antibody reactivity, qualitative and quantitative data on B- and Z-DNA in cells were determined. Anti-B-DNA immunoreactivity gradually declined throughout nucleated fibers, with a precipitous decrease at approximately 90 microns. Anti-Z-DNA antibody binding decreased with a sudden loss of immunoreactivity at approximately 90 microns. The pattern of anti-B- and Z-DNA staining correlates with the loss of alpha-crystallin immunoreactivity, the major lens crystallin, and decreased eosin staining of proteins. Germinative zone cell nuclei showed the highest DNA probe binding values, followed by the superficial fibers, central zone, middle fibers, and deep fibers. The presence of single-stranded (ss)DNA in deeper fibers was detected by anti-ss-DNA antibodies. This is indicative of DNA degradation. These observations suggest that a dramatic reorganization of lens fiber cells' supramolecular order occurs at approximately 90 microns, the phase transition zone.
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Affiliation(s)
- C E Gagna
- Department of Ophthalmology, University of Medicine and Dentistry of New Jersey-Medical School, Newark 07103, USA
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17
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Walker PR, Sikorska M. New aspects of the mechanism of DNA fragmentation in apoptosis. Biochem Cell Biol 1997. [DOI: 10.1139/o97-053] [Citation(s) in RCA: 96] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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18
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Bassnett S, Mataic D. Chromatin degradation in differentiating fiber cells of the eye lens. J Cell Biol 1997; 137:37-49. [PMID: 9105035 PMCID: PMC2139849 DOI: 10.1083/jcb.137.1.37] [Citation(s) in RCA: 147] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/1996] [Revised: 10/28/1996] [Indexed: 02/04/2023] Open
Abstract
During development, the lens of the eye becomes transparent, in part because of the elimination of nuclei and other organelles from the central lens fiber cells by an apoptotic-like mechanism. Using confocal microscopy we showed that, at the border of the organelle-free zone (OFZ), fiber cell nuclei became suddenly irregular in shape, with marginalized chromatin. Subsequently, holes appeared in the nuclear envelope and underlying laminae, and the nuclei collapsed into condensed, spherical structures. Nuclear remnants, containing DNA, histones, lamin B2, and fragments of nuclear membrane, were detected deep in the OFZ. We used in situ electrophoresis to demonstrate that fragmented DNA was present only in cells bordering the OFZ. Confocal microscopy of terminal deoxynucleotidyl transferase (TdT)-labeled lens slices confirmed that DNA fragmentation was a relatively late event in fiber differentiation, occurring after the loss of the nuclear membrane. DNA fragments with 3'-OH or 3'-PO(4) ends were not observed elsewhere in the lens under normal conditions, although they could be produced by pretreatment with DNase I or micrococcal nuclease, respectively. Dual labeling with TdT and an antibody against protein disulfide isomerase, an ER-resident protein, revealed a distinct spatial and temporal gap between the disappearance of ER and nuclear membranes and the onset of DNA degradation. Thus, fiber cell chromatin disassembly differs significantly from classical apoptosis, in both the sequence of events and the time course of the process. The fact that DNA degradation occurs only after the disappearance of mitochondrial, ER, and nuclear membranes suggests that damage to intracellular membranes may be an initiating event in nuclear breakdown.
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Affiliation(s)
- S Bassnett
- Department of Ophthalmology and Visual Sciences, Washington University Medical School, St. Louis, Missouri 63110-1093, USA.
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19
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Zelenka PS, Gao CY, Rampalli A, Arora J, Chauthaiwale V, He HY. Cell cycle regulation in the lens: Proliferation, quiescence, apoptosis and differentiation. Prog Retin Eye Res 1997. [DOI: 10.1016/s1350-9462(96)00024-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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20
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Ucker DS. Death and dying in the immune system. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 1997; 41:179-218. [PMID: 9204146 DOI: 10.1016/s1054-3589(08)61059-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- D S Ucker
- Department of Microbiology and Immunology, University of Illinois College of Medicine, Chicago 60612, USA
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21
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Abstract
In this paper, the more recent literature pertaining to differentiation in the developing vertebrate lens is reviewed in relation to previous work. The literature reviewed reveals that the developing lens has been, and will continue to be, a useful model system for the examination of many fundamental processes occurring during embryonic development. Areas of lens development reviewed here include: the induction and early embryology of the lens; lens cell culture techniques; the role of growth factors and cytokines; the involvement of gap junctions in lens cell-cell communication; the role of cell adhesion molecules, integrins, and the extracellular matrix; the role of the cytoskeleton; the processes of programmed cell death (apoptosis) and lens fibre cell denucleation; the involvement of Pax and Homeobox genes; and crystallin gene regulation. Finally, some speculation is provided as to possible directions for further research in lens development.
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Affiliation(s)
- M A Wride
- Department of Physiology, University of Alberta, Edmonton, Canada
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22
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Oberhammer F, Froschl G, Tiefenbacher R, Inayat-Hussain SH, Cain K, Stopper H. Hepatocyte death following transforming growth factor-beta 1 addition. Microsc Res Tech 1996; 34:247-58. [PMID: 8743412 DOI: 10.1002/(sici)1097-0029(19960615)34:3<247::aid-jemt7>3.0.co;2-m] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Apoptosis is a morphological term which describes a sequence of events finally leading to cell death. In epithelial organs, induction of cell death is closely linked to an inhibitor of epithelial growth, transforming growth factor-beta 1 (TGF-beta 1). In this paper, we describe the morphology of TGF-beta 1-induced apoptosis in hepatocytes of the hyperplastic liver and primary cultures. Chromatin condensation, a hallmark of apoptosis, was observed in primary hepatocytes by confocal and vital UV microscopy. In addition, we have applied the morphological detection of DNA strand breaks both by in situ tailing (ISTAIL) and in situ nick translation (ISNT).
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Affiliation(s)
- F Oberhammer
- MRC Toxicology Unit, University of Leicester, United Kingdom
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Torriglia A, Chaudun E, Chany-Fournier F, Jeanny JC, Courtois Y, Counis MF. Involvement of DNase II in nuclear degeneration during lens cell differentiation. J Biol Chem 1995; 270:28579-85. [PMID: 7499373 DOI: 10.1074/jbc.270.48.28579] [Citation(s) in RCA: 85] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The characterization of DNase II and DNase I activity was undertaken to discriminate their different roles in physiological nuclear degradation during lens fiber cell differentiation. The activity of both nucleases determined in a new assay allows to discriminate DNase II from DNase I in the same extract. In fibers, both types of nuclease activities are found and appear higher than in epithelial cells. Specific polyclonal antibodies directed against these two nucleases reveal by Western blot analysis the presence of various DNase isoforms. DNase II like-nuclease, present in fibers, is represented by three major bands (60,23, and 18 kDa), which are not detected, at least for two of them (60 and 23 kDa), in epithelial cells. DNase I like-nuclease pattern in fiber cells shows a single 32-kDa band, while several bands can be detected in epithelial cells. Immunocytochemistry studies show both nucleases present in lens cell sections. DNase II is, as usual, in cytoplasm of epithelial cells, but it appears strikingly concentrated in the nuclei of fibers. DNase I is always concentrated in nuclei of epithelial and fiber cells. DNA degradation observed in agarose gels shows that DNase II-activating medium cleaves the DNA from fiber cells more efficiently than DNase I-activating buffer. In addition, DNase II antibody is able to prevent this degradation. These results suggest a specific involvement of DNase II in nuclear degradation during lens cell differentiation.
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Affiliation(s)
- A Torriglia
- XR 118 INSERM, Association Claude Bernard, Paris, France
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