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D L Vaux

Publications and source records attributed to D L Vaux.

At least 19 recordsLinked to original sources
PubMed2001

TNF and CD95 promote IL-8 gene transactivation via independent elements in colon carcinoma cells.

The pro-inflammatory cytokine interleukin-8 (IL-8) is produced by HT29 colon epithelial cells following engagement of either CD95 or tumour necrosis factor (TNF) receptors. While the IL-8 promotor elements activated by TNF are well characterised, those responsible for induction of IL-8 by CD95 are unknown. We examined the pathway for CD95 induced IL-8 secretion using two luciferase reporter constructs; the first comprising approximately 500 bp of the IL-8 promotor that includes the nuclear factor kappa B (NFkappaB), C/EBP and AP-1 sites known to be involved in TNF mediated IL-8 induction; the second that encompasses these elements but extends approximately 1.1 kb further upstream. Although IL-8 mRNA and protein were produced in response to either TNF or CD95 ligation, only TNF induced an increase in the reporter activity of the promoter constructs. Nevertheless, IL-8 induction by CD95 resulted primarily from increased transcription and not from an increase in IL-8 mRNA stability. These results suggest that promoter elements/enhancers involved in CD95 mediated IL-8 induction are distinct from those used by TNF and not contained within the 1.6 kb region immediately upstream of the initiation codon.

Colon↗
PubMed2001

Inhibitor of apoptosis proteins and their relatives: IAPs and other BIRPs.

SUMMARY: Apoptosis is a physiological cell death process important for development, homeostasis and the immune defence of multicellular animals. The key effectors of apoptosis are caspases, cysteine proteases that cleave after aspartate residues. The inhibitor of apoptosis (IAP) family of proteins prevent cell death by binding to and inhibiting active caspases and are negatively regulated by IAP-binding proteins, such as the mammalian protein DIABLO/Smac. IAPs are characterized by the presence of one to three domains known as baculoviral IAP repeat (BIR) domains and many also have a RING-finger domain at their carboxyl terminus. More recently, a second group of BIR-domain-containing proteins (BIRPs) have been identified that includes the mammalian proteins Bruce and Survivin as well as BIR-containing proteins in yeasts and Caenorhabditis elegans. These Survivin-like BIRPs regulate cytokinesis and mitotic spindle formation. In this review, we describe the IAPs and other BIRPs, their evolutionary relationships and their subcellular and tissue localizations.

Amino Acid Sequence↗
PubMed2001

Direct inhibition of caspase 3 is dispensable for the anti-apoptotic activity of XIAP.

XIAP is a mammalian inhibitor of apoptosis protein (IAP). To determine residues within the second baculoviral IAP repeat (BIR2) required for inhibition of caspase 3, we screened a library of BIR2 mutants for loss of the ability to inhibit caspase 3 toxicity in the yeast Schizosaccharomyces pombe. Four of the mutations, not predicted to affect the structure of the BIR fold, clustered together on the N-terminal region that flanks BIR2, suggesting that this is a site of interaction with caspase 3. Introduction of these mutations into full-length XIAP reduced caspase 3 inhibitory activity up to 500-fold, but did not affect its ability to inhibit caspase 9 or interact with the IAP antagonist DIABLO. Furthermore, these mutants retained full ability to inhibit apoptosis in transfected cells, demonstrating that although XIAP is able to inhibit caspase 3, this activity is dispensable for inhibition of apoptosis by XIAP in vivo.

Amino Acid Sequence↗
PubMed2001

DIABLO promotes apoptosis by removing MIHA/XIAP from processed caspase 9.

MIHA is an inhibitor of apoptosis protein (IAP) that can inhibit cell death by direct interaction with caspases, the effector proteases of apoptosis. DIABLO is a mammalian protein that can bind to IAPs and antagonize their antiapoptotic effect, a function analogous to that of the proapoptotic Drosophila molecules, Grim, Reaper, and HID. Here, we show that after UV radiation, MIHA prevented apoptosis by inhibiting caspase 9 and caspase 3 activation. Unlike Bcl-2, MIHA functioned after release of cytochrome c and DIABLO from the mitochondria and was able to bind to both processed caspase 9 and processed caspase 3 to prevent feedback activation of their zymogen forms. Once released into the cytosol, DIABLO bound to MIHA and disrupted its association with processed caspase 9, thereby allowing caspase 9 to activate caspase 3, resulting in apoptosis.

Apoptosis↗
PubMed2001

Two kinds of BIR-containing protein - inhibitors of apoptosis, or required for mitosis.

The baculoviral IAP repeat (BIR) is a zinc-binding fold. Some BIR-containing proteins (BIRCs), including several from insect viruses, insects and vertebrates, are inhibitors of cell death and act by binding to active caspases. Their ability to do so can be antagonized by pro-apoptotic insect proteins such as Grim, HID and Reaper, or the mammalian protein Diablo/Smac. Members of one structurally distinct subgroup of BIR-containing proteins, which are present in yeasts and Caenorhabditis elegans as well as insects and vertebrates, do not act as caspase inhibitors; instead, they are required for chromosome segregation and cytokinesis, and act in concert with inner centromere protein (INCENP) homologues and aurora kinase homologues.

Animals↗
PubMed2000

Survivin and the inner centromere protein INCENP show similar cell-cycle localization and gene knockout phenotype.

BACKGROUND: Survivin is a mammalian protein that carries a motif typical of the inhibitor of apoptosis (IAP)proteins, first identified in baculoviruses. Although baculoviral IAP proteins regulate cell death, the yeast Survivin homolog Bir1 is involved in cell division. To determine the function of Survivin in mammals, we analyzed the pattern of localization of Survivin protein during the cell cycle, and deleted its gene by homologous recombination in mice. RESULTS: In human cells, Survivin appeared first on centromeres bound to a novel para-polar axis during prophase/metaphase, relocated to the spindle midzone during anaphase/telophase, and disappeared at the end of telophase. In the mouse, Survivin was required for mitosis during development. Null embryos showed disrupted microtubule formation, became polyploid, and failed to survive beyond 4.5days post coitum. This phenotype, and the cell-cycle localization of Survivin, resembled closely those of INCENP. Because the yeast homolog of INCENP, Sli15, regulates the Aurora kinase homolog Ipl1p, and the yeast Survivin homolog Bir1 binds to Ndc10p, a substrate of Ipl1p, yeast Survivin, INCENP and Aurora homologs function in concert during cell division. CONCLUSIONS: In vertebrates, Survivin and INCENP have related roles in mitosis, coordinating events such as microtubule organization, cleavage-furrow formation and cytokinesis. Like their yeast homologs Bir1 and Sli15, they may also act together with the Aurora kinase.

Amino Acid Sequence↗
PubMed2000

Identification of DIABLO, a mammalian protein that promotes apoptosis by binding to and antagonizing IAP proteins.

To identify proteins that bind mammalian IAP homolog A (MIHA, also known as XIAP), we used coimmuno-precipitation and 2D immobilized pH gradient/SDS PAGE, followed by electrospray ionization tandem mass spectrometry. DIABLO (direct IAP binding protein with low pI) is a novel protein that can bind MIHA and can also interact with MIHB and MIHC and the baculoviral IAP, OpIAP. The N-terminally processed, IAP-interacting form of DIABLO is concentrated in membrane fractions in healthy cells but released into the MIHA-containing cytosolic fractions upon UV irradiation. As transfection of cells with DIABLO was able to counter the protection afforded by MIHA against UV irradiation, DIABLO may promote apoptosis by binding to IAPs and preventing them from inhibiting caspases.

Amino Acid Sequence↗
PubMed2000

Apoptosis genes and autoimmunity.

To try to understand autoimmunity, attention has often fallen on the process of cell death. After all, apoptosis is used during selection of immunocytes, cells in the target organs end up dying and mutations to cell death genes have been found in some autoimmune diseases. Furthermore, some autoimmune-prone mice fail to develop disease when certain cell death genes are deleted, and transgenic mice expressing other cell death genes develop autoimmunity. However, only a tiny proportion of human autoimmune disease is associated with mutations to individual genes and even in these rare cases the genetic background has a major influence on the severity of disease. An understanding of the pathophysiology of common autoimmune diseases will require elucidation of many different systems that interact in complex ways, of which the process of apoptosis is just one.

Animals↗
PubMed1999

Role for yeast inhibitor of apoptosis (IAP)-like proteins in cell division.

Inhibitors of apoptosis (IAPs) are a family of proteins that bear baculoviral IAP repeats (BIRs) and regulate apoptosis in vertebrates and Drosophila melanogaster. The yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe both encode a single IAP, designated BIR1 and bir1, respectively, each of which bears two BIRs. In rich medium, BIR1 mutant S. cerevisiae underwent normal vegetative growth and mitosis. Under starvation conditions, however, BIR1 mutant diploids formed spores inefficiently, instead undergoing pseudohyphal differentiation. Most spores that did form failed to survive beyond two divisions after germination. bir1 mutant S. pombe spores also died in the early divisions after spore germination and became blocked at the metaphase/anaphase transition because of an inability to elongate their mitotic spindle. Rather than inhibiting caspase-mediated cell death, yeast IAP proteins have roles in cell division and appear to act in a similar way to the IAPs from Caenorhabditis elegans and the mammalian IAP Survivin.

Amino Acid Sequence↗
PubMed1999

Insights from Bcl-2 and Myc: malignancy involves abrogation of apoptosis as well as sustained proliferation.

The chromosome translocations typifying Burkitt's lymphoma and follicular lymphoma deregulate very different oncogenes, myc and bcl-2. Transgenic mouse models have illuminated how each contributes to lymphomagenesis. Constitutive myc expression provokes sustained cell proliferation and retards differentiation. However, the resulting expansion in cell number is self-limiting, because the cells remain dependent on cytokines and undergo apoptosis when these become limiting. In contrast, bcl-2 is the prototype of a new class of oncogene that enhances cell survival but does not promote proliferation. Coexpression of these genes leads to the rapid transformation of lymphocytes, probably because each can counter an antioncogenic aspect of the other. Several close homologues of Bcl-2 also enhance cell survival and are thus potential oncogenes; each is essential for maintenance of particular major organs. More distant Bcl-2 relatives instead promote apoptosis and can be regarded as tumor suppressors. For many but not all apoptic signals, the balance between these competing activities determines cell survival. Learning how to adjust the apoptotic threshold in cancer cells should promote development of more effective therapeutic strategies.

Animals↗
PubMed1999

Inhibition of apoptosis and clonogenic survival of cells expressing crmA variants: optimal caspase substrates are not necessarily optimal inhibitors.

To study the role of various caspases during apoptosis, we have designed a series of caspase inhibitors based on the cowpox virus cytokine response modifier A (crmA) protein. Wild-type crmA inhibits caspases 1 and 8 and thereby protects cells from apoptosis triggered by ligation of CD95 or tumour necrosis factor (TNF) receptors, but it does not protect against death mediated by other caspases. By replacing the tetrapeptide pseudosubstrate region of crmA (LVAD) with tetrapeptides that are optimal substrates for the different families of caspases, or with the four residues from the cleavage site of the baculovirus protein p35 (DQMD), we have generated a family of caspase inhibitors that show altered ability to protect against cell death. Although DEVD is the optimal substrate for caspase 3, crmA DEVD was degraded rapidly and was a weaker inhibitor than crmA DQMD, which was not degraded. Unlike wild-type crmA and crmA DEVD, crmA DQMD was able to inhibit apoptosis caused by direct activation of caspase 3 and protected lymphoid cells from death induced by radiation and dexamethasone. Significantly, the protected cells were capable of sustained growth.

Amino Acid Sequence↗
PubMed1999

Solution structure of a baculoviral inhibitor of apoptosis (IAP) repeat.

Members of the inhibitor of apoptosis (IAP) family of proteins are able to inhibit cell death following viral infection, during development or in cell lines in vitro. All IAP proteins bear one or more baculoviral IAP repeats (BIRs). Here we describe the solution structure of the third BIR domain from the mammalian IAP homolog B (MIHB/c-IAP-1). The BIR domain has a novel fold that is stabilized by zinc tetrahedrally coordinated by one histidine and three cysteine residues. The structure consists of a series of short alpha-helices and turns with the zinc packed in an unusually hydrophobic environment created by residues that are highly conserved among all BIRs.

Amino Acid Sequence↗
PubMed1999

Solution structure and mutagenesis of the caspase recruitment domain (CARD) from Apaf-1.

Activation of procaspase-9, a key component of the apoptosis mechanism, requires the interaction of its caspase recruitment domain (CARD) with the CARD in the adaptor protein Apaf-1. Using nuclear magnetic resonance spectroscopy and mutagenesis we have determined the structure of the CARD from Apaf-1 and the residues important for binding the CARD in procaspase-9. Apaf-1's CARD contains seven short alpha-helices with the core six helices arranged in an antiparallel manner. Residues in helix 2 have a central role in mediating interaction with procaspase-9 CARD. This interaction surface is distinct from that proposed based on the structure of the CARD from RAIDD, but is coincident with that of the structurally similar FADD death effector domain and the Apaf-1 CARD interface identified by crystallographic studies.

Adaptor Proteins, Signal Transducing↗