scholarly journals Induction of apoptosis by lipophilic activators of CTP:phosphocholine cytidylyltransferase α (CCTα)

2005 ◽  
Vol 392 (3) ◽  
pp. 449-456 ◽  
Author(s):  
Thomas A. Lagace ◽  
Neale D. Ridgway
Keyword(s):  
Nuclear Export ◽  
Oleyl Alcohol ◽  
Caspase Cleavage ◽  
Ctp:Phosphocholine Cytidylyltransferase ◽  
Transient Activation ◽  
Initial Effect ◽  
Induction Of Apoptosis ◽  
Induced Apoptosis ◽  
Rate Limiting ◽  
Phosphatidylcholine Synthesis

Farnesol (FOH) inhibits the CDP-choline pathway for PtdCho (phosphatidylcholine) synthesis, an activity that is involved in subsequent induction of apoptosis. Interestingly, the rate-limiting enzyme in this pathway, CCTα (CTP:phosphocholine cytidylyltransferase α), is rapidly activated, cleaved by caspases and exported from the nucleus during FOH-induced apoptosis. The purpose of the present study was to determine how CCTα activity and PtdCho synthesis contributed to induction of apoptosis by FOH and oleyl alcohol. Contrary to previous reports, we show that the initial effect of FOH and oleyl alcohol was a rapid (10–30 min) and transient activation of PtdCho synthesis. During this period, the mass of DAG (diacylglycerol) decreased by 40%, indicating that subsequent CDP-choline accumulation and inhibition of PtdCho synthesis could be due to substrate depletion. At later time points (>1 h), FOH and oleyl alcohol promoted caspase cleavage and nuclear export of CCTα, which was prevented by treatment with oleate or DiC8 (dioctanoylglycerol). Protection from FOH-induced apoptosis required CCTα activity and PtdCho synthesis since (i) DiC8 and oleate restored PtdCho synthesis, but not endogenous DAG levels, and (ii) partial resistance was conferred by stable overexpression of CCTα and increased PtdCho synthesis in CCTα-deficient MT58 cells. These results show that DAG depletion by FOH or oleyl alcohol could be involved in inhibition of PtdCho synthesis. However, decreased DAG was not sufficient to induce apoptosis provided nuclear CCTα and PtdCho syntheses were sustained.

scholarly journals Caspase Processing and Nuclear Export of CTP:Phosphocholine Cytidylyltransferase α during Farnesol-Induced Apoptosis

2002 ◽  
Vol 22 (13) ◽  
pp. 4851-4862 ◽  
Author(s):  
Thomas A. Lagace ◽  
Jessica R. Miller ◽  
Neale D. Ridgway
Keyword(s):  
Nuclear Envelope ◽  
Nuclear Localization ◽  
Cho Cells ◽  
Nuclear Localization Signal ◽  
Nuclear Export ◽  
Cleavage Site ◽  
Caspase Cleavage ◽  
Ctp:Phosphocholine Cytidylyltransferase ◽  
Localization Signal ◽  
Induced Apoptosis

ABSTRACT CTP:phosphocholine cytidylyltransferase alpha (CCTα) is a nuclear enzyme that catalyzes the rate-limiting step in the CDP-choline pathway, the primary route for synthesis of phosphatidylcholine (PtdCho) in eukaryotic cells. Induction of apoptosis by farnesol (FOH) and other cytotoxic drugs has been shown to alter PtdCho synthesis via the CDP-choline pathway. Here we report that FOH-induced apoptosis in CHO cells caused a dose-dependent activation of CCTα and inhibition of the final step in the pathway, resulting in a biphasic effect on PtdCho synthesis. Activation of CCTα was accompanied by enzyme translocation to the nuclear envelope within 30 min of FOH addition to cells. Following translocation to membranes, CCTα was exported from the nucleus and underwent caspase-mediated proteolysis that coincided with poly(ADP-ribose) polymerase cleavage. Site-directed mutagenesis and in vivo and in vitro expression studies mapped a caspase 6 and/or 8 cleavage site to TEED28↓G, the final residue in the CCTα nuclear localization signal. Nuclear export of CCTα appeared to be an active process in FOH-treated CHO cells that was independent of caspase removal of the nuclear localization signal. Caspase cleavage of CCTα occurred during UV or chelerythrine-induced apoptosis; however, nuclear membrane translocation and nuclear export were not evident under these conditions. Thus, caspase cleavage of CCTα was a late feature of several apoptotic programs that occurred in the nucleus or at the nuclear envelope. Activation and nuclear export of CCTα were early events in FOH-induced apoptosis that contributed to altered PtdCho synthesis and, in conjunction with caspase cleavage, excluded CCTα from the nucleus.

scholarly journals Caspase-Dependent Cleavage of c-Abl Contributes to Apoptosis

2003 ◽  
Vol 23 (8) ◽  
pp. 2790-2799 ◽  
Author(s):  
Daniela Barilà ◽  
Alessandra Rufini ◽  
Ivano Condò ◽  
Natascia Ventura ◽  
Karel Dorey ◽  
...  
Keyword(s):  
Nuclear Export ◽  
Nuclear Export Signal ◽  
Death Receptor ◽  
Kinase Domain ◽  
Actin Binding ◽  
Caspase Cleavage ◽  
Nonreceptor Tyrosine Kinase ◽  
Nuclear Localization Signals ◽  
Induced Apoptosis ◽  
Export Signal

ABSTRACT The nonreceptor tyrosine kinase c-Abl may contribute to the regulation of apoptosis. c-Abl activity is induced in the nucleus upon DNA damage, and its activation is required for execution of the apoptotic program. Recently, activation of nuclear c-Abl during death receptor-induced apoptosis has been reported; however, the mechanism remains largely obscure. Here we show that c-Abl is cleaved by caspases during tumor necrosis factor- and Fas receptor-induced apoptosis. Cleavage at the very C-terminal region of c-Abl occurs mainly in the cytoplasmic compartment and generates a 120-kDa fragment that lacks the nuclear export signal and the actin-binding region but retains the intact kinase domain, the three nuclear localization signals, and the DNA-binding domain. Upon caspase cleavage, the 120-kDa fragment accumulates in the nucleus. Transient-transfection experiments show that cleavage of c-Abl may affect the efficiency of Fas-induced cell death. These data reveal a novel mechanism by which caspases can recruit c-Abl to the nuclear compartment and to the mammalian apoptotic program.

scholarly journals Differential dephosphorylation of CTP:phosphocholine cytidylyltransferase upon translocation to nuclear membranes and lipid droplets

2020 ◽  
Vol 31 (10) ◽  
pp. 1047-1059 ◽  
Author(s):  
Lambert Yue ◽  
Michael J. McPhee ◽  
Kevin Gonzalez ◽  
Mark Charman ◽  
Jonghwa Lee ◽  
...  
Keyword(s):  
Lipid Droplets ◽  
Nuclear Membranes ◽  
Ctp:Phosphocholine Cytidylyltransferase ◽  
P Domain ◽  
Rate Limiting ◽  
Phosphatidylcholine Synthesis ◽  
Sustained Phosphorylation

The translocation of CCTα, the rate-limiting enzyme for phosphatidylcholine synthesis, to nuclear membranes and nuclear lipid droplets results in reversible dephosphorylation of S319 and sustained phosphorylation of Y359+S362. Independent regulation of these phosphosites in the P-domain of CCTα is required for activation on nuclear membranes.

scholarly journals Insulin-like growth factor-binding protein-3 is partially responsible for high-serum-induced apoptosis in PC-3 prostate cancer cells

1999 ◽  
Vol 163 (3) ◽  
pp. 487-494 ◽  
Author(s):  
R Rajah ◽  
A Khare ◽  
PD Lee ◽  
P Cohen
Keyword(s):  
Prostate Cancer ◽  
Binding Protein ◽  
High Serum ◽  
Apoptotic Index ◽  
Serum Concentrations ◽  
Induction Of Apoptosis ◽  
Induced Apoptosis ◽  
Dose Dependent ◽  
Igfbp 3

Cells are known to undergo apoptosis when cultured in high serum concentrations. However, the serum factors responsible for this induction of apoptosis have not been identified. The IGF-binding protein-3 (IGFBP-3), a negative growth regulator, is found at concentrations of 5 microgram/ml in serum. We have recently demonstrated that IGFBP-3 induces apoptosis in PC-3 cells, a prostate cancer cell line, at a concentration of 500 ng/ml. In this communication, we demonstrate the role of IGFBP-3 as one of the apoptosis-inducing agents in high serum concentrations. Treatment of PC-3 cells with increasing concentrations (40% to 90%) of intact human serum (HS) resulted in a dose-dependent decrease in cell growth. Valinomycin, an ionophore, was used as a positive control to measure the induction of apoptosis by serum treatment in PC-3 cells. Treatment with 90% serum showed significant suppression of growth (P<0.001) compared with the effect of 10% serum. Treatment with increasing concentrations of HS (40% to 90%) resulted in a dose-dependent increase in apoptosis. Treatment with 90% HS showed a 10-fold increase in apoptotic index compared with cells treated with 10% HS. Treatment of PC-3 cells with IGFs and IGFBP-3-depleted 90% human sera (depleted serum=DS) demonstrated significantly lower levels of apoptosis (50% reduction in the effect of 90% HS) suggesting a role of IGFBP-3 in inducing apoptosis in high serum concentration. Furthermore, treatment with DS supplemented with recombinant IGFBP-3 (500 ng/ml) brought the apoptotic index down close to the level of apoptosis induced by 90% intact serum treatment (P<0.001). However, DS supplemented with physiological concentrations of IGFs (500 ng/ml) showed only partial recovery of cell survival demonstrated by 90% DS. This data indicates that IGFBP-3 is one of the factors in serum that is responsible for high-serum-induced apoptosis.

4-Acetyl-12,13-Epoxyl-9-Trichothecene-3,15-Diol from Isaria japonica Mediates Apoptosis of Rat Bladder Carcinoma NBT-II Cells by Decreasing Anti-apoptotic Bcl-2 Expression and Increasing Pro-apoptotic Bax Expression

2004 ◽  
Vol 32 (03) ◽  
pp. 377-387 ◽  
Author(s):  
Hyung-Jin Kim ◽  
Seon Il Jang ◽  
Young-Jun Kim ◽  
Hyun-Ock Pae ◽  
Hae-Young Won ◽  
...  
Keyword(s):  
Cell Death ◽  
Bladder Carcinoma ◽  
Cytotoxic Effect ◽  
Caspase 3 ◽  
Apoptotic Cell ◽  
Morphological Changes ◽  
Rat Bladder ◽  
Apoptotic Protein ◽  
Induction Of Apoptosis ◽  
Induced Apoptosis

We studied the effect of 4-acetyl-12,13-epoxyl-9-trichothecene-3,15-diol (AETD) isolated from Isaria japonica, one of the most popular Chinese fungal medicines, on the induction of apoptosis in rat bladder carcinoma NBT-II cells. AETD was cytotoxic to NBT-II cells, and this cytotoxic effect appears to be attributed to its induction of apoptotic cell death, as AETD induced nuclear morphological changes and internucleosomal DNA fragmentation, and increased the proportion of hypodiploid cells and activity of caspase-3. AETD treatment also decreased the expression of the anti-apoptotic protein Bcl-2 and increased the expression of the pro-apoptotic protein Bax. These results provide important information in understanding the mechanism(s) of AETD-induced apoptosis.

Integrated control of cell proliferation and cell death by the c- myc oncogene

1994 ◽  
Vol 345 (1313) ◽  
pp. 269-275 ◽  
Keyword(s):  
Cell Proliferation ◽  
Cell Death ◽  
Transcriptional Activation ◽  
Dynamic Equilibrium ◽  
Growth Arrest ◽  
Deletion Mapping ◽  
Potent Inducer ◽  
Cellular Environment ◽  
Induction Of Apoptosis ◽  
Induced Apoptosis

Regulation of multicellular architecture involves a dynamic equilibrium between cell proliferation, differentiation with consequent growth arrest, and cell death. Apoptosis is one particular form of active cell death that is extremely rapid and characterized by auto-destruction of chromatin, cellular blebbing and condensation, and vesicularization of internal components. The c- myc proto-oncogene encodes an essential component of the cell’s proliferative machinery and its deregulated expression is implicated in most neoplasms. Intriguingly, c- myc can also act as a potent inducer of apoptosis. Myc-induced apoptosis occurs only in cells deprived of growth factors or forcibly arrested with cytostatic drugs. Myc-induced apoptosis is dependent upon the level at which it is expressed and deletion mapping shows that regions of c-Myc required for apoptosis overlap with regions necessary for co-transformation, autoregulation, inhibition of differentiation, transcriptional activation and sequence-specific DNA binding. Moreover, induction of apoptosis by c-Myc requires association with c-Myc’s heterologous partner, Max. All of this strongly implies that c-Myc drives apoptosis through a transcriptional mechanism: presumably by modulation of target genes. Two simple models can be invoked to explain the induction of apoptosis by c-Myc. One holds that death arises from a conflict in growth signals which is generated by the inappropriate or unscheduled expression of c-Myc under conditions that would normally promote growth arrest. In this ‘Conflict’ model, induction of apoptosis is not a normal function of c-Myc but a pathological manifestation of its deregulation. It thus has significance only for models of carcinogenic progression in which myc genes are invariably disrupted. The other model holds that induction of apoptosis is a normal obligate function of c-Myc which is modulated by specific survival factors. Thus, every cell that enters the cycle invokes an obligate abort suicide pathway which must be continuously suppressed by signals from the immediate cellular environment for the proliferating cell to survive. Evidence will be presented supporting this second ‘Dual Signal’ model for cell growth and survival, and its widespread implications will be discussed.

scholarly journals Adenovirus E1B 55-Kilodalton Protein Is a p53-SUMO1 E3 Ligase That Represses p53 and Stimulates Its Nuclear Export through Interactions with Promyelocytic Leukemia Nuclear Bodies

2010 ◽  
Vol 84 (23) ◽  
pp. 12210-12225 ◽  
Author(s):  
Mario A. Pennella ◽  
Yue Liu ◽  
Jennifer L. Woo ◽  
Chongwoo A. Kim ◽  
Arnold J. Berk
Keyword(s):  
Nuclear Export ◽  
P53 Mutation ◽  
Promyelocytic Leukemia ◽  
Nuclear Bodies ◽  
Live Cells ◽  
High Concentration ◽  
Sumoylation Site ◽  
Pml Nuclear Bodies ◽  
Induced Apoptosis

ABSTRACT Oncogenic transformation by adenovirus E1A and E1B-55K requires E1B-55K inhibition of p53 activity to prevent E1A-induced apoptosis. During viral infection, E1B-55K and E4orf6 substitute for the substrate-binding subunits of the host cell cullin 5 class of ubiquitin ligases, resulting in p53 polyubiquitinylation and proteasomal degradation. Here we show that E1B-55K alone also functions as an E3 SUMO1-p53 ligase. Fluorescence microscopy studies showed that E1B-55K alone, in the absence of other viral proteins, causes p53 to colocalize with E1B-55K in promyelocytic leukemia (PML) nuclear bodies, nuclear domains with a high concentration of sumoylated proteins. Photobleaching experiments with live cells revealed that E1B-55K tethering of p53 in PML nuclear bodies decreases the in vivo nuclear mobility of p53 nearly 2 orders of magnitude. E1B-55K-induced p53 sumoylation contributes to maximal inhibition of p53 function since mutation of the major p53 sumoylation site decreases E1B-55K-induced p53 sumoylation, tethering in PML nuclear bodies, and E1B-55K inhibition of p53 activity. Mutation of the E1B-55K sumoylation site greatly inhibits E1B-55K association with PML nuclear bodies and the p53 nuclear export to cytoplasmic aggresomes observed in E1A-E1B-transformed cells. Purified E1B-55K and p53 form high-molecular-weight complexes potentially through the formation of a network of E1B-55K dimers bound to the N termini of p53 tetramers. In support of this model, a p53 mutation that prevents tetramer formation greatly reduces E1B-55K-induced tethering in PML nuclear bodies and p53 nuclear export. These data indicate that E1B-55K's association with PML nuclear bodies inactivates p53 by first sequestering it in PML nuclear bodies and then greatly facilitating its nuclear export.

scholarly journals The double-stranded RNA-induced apoptosis pathway is involved in the cytopathogenicity of cytopathogenic Bovine viral diarrhea virus

2006 ◽  
Vol 87 (10) ◽  
pp. 2961-2970 ◽  
Author(s):  
Daisuke Yamane ◽  
Kentaro Kato ◽  
Yukinobu Tohya ◽  
Hiroomi Akashi
Keyword(s):  
Cell Death ◽  
Bovine Viral Diarrhea Virus ◽  
Persistent Infection ◽  
Yield Potential ◽  
Bovine Viral Diarrhea ◽  
Diarrhea Virus ◽  
Viral Diarrhea ◽  
Induction Of Apoptosis ◽  
Induced Apoptosis ◽  
Viral Diarrhea Virus

Bovine viral diarrhea virus (BVDV), which is classified in the genus Pestivirus, family Flaviviridae, can be divided into two biotypes according to its ability to induce a cytopathic effect in tissue culture cells. The mechanisms through which cytopathogenic (cp) BVDV induces cell death and non-cytopathogenic (ncp) BVDV causes persistent infection without producing cell death remain unclear. Here, it was found that the overexpression of four apoptosis-related cellular mRNAs in cells infected with cpBVDV could also be caused by synthetic dsRNA. In fact, it was found that the amount of dsRNA produced by cpBVDV considerably exceeded the amount yielded by ncpBVDV. To evaluate the possible involvement of dsRNA in the induction of apoptosis, this study examined whether RNAi-mediated depletion of two dsRNA-reactive cellular factors, dsRNA-dependent protein kinase and 2′,5′-oligoadenylate synthetase 1, resulted in the prevention of cpBVDV-induced apoptosis. Although the induction of apoptosis was reduced after the suppression of either factor alone, the simultaneous silencing of both factors resulted in an almost complete inhibition of apoptosis without affecting viral titre. These results showed that dsRNA is the main trigger of apoptosis in cpBVDV-infected cells and that the cytopathogenicity of BVDV depends on the yield potential of dsRNA. In contrast, ncpBVDV yielded minimal levels of dsRNA, thereby establishing a persistent infection without inducing apoptosis. This report supports the significance of viral dsRNA as a trigger of innate immune responses.

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