Nuclear localization of cyclin B1 regulates DNA damage–induced apoptosis

Blood ◽  
2003 ◽  
Vol 101 (5) ◽  
pp. 1928-1933 ◽  
Author(s):  
Lisa A. Porter ◽  
I. Howard Cukier ◽  
Jonathan M. Lee
Keyword(s):  
Dna Damage ◽  
Nuclear Export ◽  
Intracellular Localization ◽  
Ectopic Expression ◽  
Cell Types ◽  
Cyclin B1 ◽  
Nuclear Accumulation ◽  
Leptomycin B ◽  
Radiation Induced ◽  
Induced Apoptosis

Some cells undergo apoptosis in response to DNA damage, whereas others do not. To understand the biochemical pathways controlling this differential response, we have studied the intracellular localization of cyclin B1 in cell types sensitive or resistant to apoptosis induced by DNA damage. We found that cyclin B1 protein accumulates in the nucleus of cells that are sensitive to γ radiation–induced apoptosis (thymocytes, lymphoid cell lines), but remains cytoplasmic in apoptosis-resistant cells (primary and transformed fibroblasts). Treatment of both cell types with leptomycin B, an inhibitor of CRM1-dependent cyclin B1 nuclear export, induces apoptosis. Furthermore, ectopic expression of cyclin B1-5xE, a protein that preferentially localizes to the nucleus, is sufficient to trigger apoptosis. Conversely, expression of cyclin B1-5xA, a predominantly cytoplasmic protein, fails to induce apoptosis. This suggests that nuclear accumulation is necessary for cyclin B1–dependent apoptosis. Our observations are consistent with the idea that localization of cyclin B1 is among the factors determining the cellular decision to undergo apoptosis in response to DNA damage.

Abundance of cyclin B1 regulates γ-radiation–induced apoptosis

Blood ◽  
2000 ◽  
Vol 95 (8) ◽  
pp. 2645-2650 ◽  
Author(s):  
Lisa A. Porter ◽  
Gurmit Singh ◽  
Jonathan M. Lee
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Mammalian Cells ◽  
Hematopoietic Cells ◽  
Cyclin B1 ◽  
Regulatory Subunit ◽  
Potent Inducer ◽  
Γ Radiation ◽  
Radiation Induced ◽  
Induced Apoptosis

Abstract γ-Radiation is a potent inducer of apoptosis. There are multiple pathways regulating DNA damage-induced apoptosis, and we set out to identify novel mechanisms regulating γ-radiation–induced apoptosis in hematopoietic cells. In this report, we present data implicating the cyclin B1 protein as a regulator of apoptotic fate following DNA damage. Cyclin B1 is the regulatory subunit of the cdc2 serine/threonine kinase, and accumulation of cyclin B1 in late G2 phase of the cell cycle is a prerequisite for mitotic initiation in mammalian cells. We find that abundance of the cyclin B1 protein rapidly increases in several mouse and human hematopoietic cells (Ramos, DP16, HL60, thymocytes) undergoing γ-radiation–induced apoptosis. Cyclin B1 accumulation occurs in all phases of the cell cycle. Antisense inhibition of cyclin B1 accumulation decreases apoptosis, and ectopic cyclin B1 expression is sufficient to induce apoptosis. These observations are consistent with the idea that cyclin B1 is both necessary and sufficient for γ-radiation-induced apoptosis.

Abundance of cyclin B1 regulates γ-radiation–induced apoptosis

Blood ◽  
2000 ◽  
Vol 95 (8) ◽  
pp. 2645-2650 ◽  
Author(s):  
Lisa A. Porter ◽  
Gurmit Singh ◽  
Jonathan M. Lee
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Mammalian Cells ◽  
Hematopoietic Cells ◽  
Cyclin B1 ◽  
Regulatory Subunit ◽  
Potent Inducer ◽  
Γ Radiation ◽  
Radiation Induced ◽  
Induced Apoptosis

γ-Radiation is a potent inducer of apoptosis. There are multiple pathways regulating DNA damage-induced apoptosis, and we set out to identify novel mechanisms regulating γ-radiation–induced apoptosis in hematopoietic cells. In this report, we present data implicating the cyclin B1 protein as a regulator of apoptotic fate following DNA damage. Cyclin B1 is the regulatory subunit of the cdc2 serine/threonine kinase, and accumulation of cyclin B1 in late G2 phase of the cell cycle is a prerequisite for mitotic initiation in mammalian cells. We find that abundance of the cyclin B1 protein rapidly increases in several mouse and human hematopoietic cells (Ramos, DP16, HL60, thymocytes) undergoing γ-radiation–induced apoptosis. Cyclin B1 accumulation occurs in all phases of the cell cycle. Antisense inhibition of cyclin B1 accumulation decreases apoptosis, and ectopic cyclin B1 expression is sufficient to induce apoptosis. These observations are consistent with the idea that cyclin B1 is both necessary and sufficient for γ-radiation-induced apoptosis.

Developmentally regulated activity of CRM1/XPO1 during early Xenopus embryogenesis

2000 ◽  
Vol 113 (3) ◽  
pp. 451-459 ◽  
Author(s):  
M. Callanan ◽  
N. Kudo ◽  
S. Gout ◽  
M. Brocard ◽  
M. Yoshida ◽  
...  
Keyword(s):  
Nuclear Export ◽  
Fluorescent Protein ◽  
Intracellular Localization ◽  
Nuclear Export Signal ◽  
Specific Inhibitor ◽  
Amino Acid Identity ◽  
Early Embryogenesis ◽  
Leptomycin B ◽  
Developmentally Regulated ◽  
Neurula Stage

In this work, we have investigated the role of CRM1/XPO1, a protein involved in specific export of proteins and RNA from the nucleus, in early Xenopus embryogenesis. The cloning of the Xenopus laevis CRM1, XCRM1, revealed remarkable conservation of the protein during evolution (96.7% amino acid identity between Xenopus and human). The protein and mRNA are maternally expressed and are present during early embryogenesis. However, our data show that the activity of the protein is developmentally regulated. Embryonic development is insensitive to leptomycin B, a specific inhibitor of CRM1, until the neurula stage. Moreover, the nuclear localization of CRM1 changes concomitantly with the appearance of the leptomycin B sensitivity. These data suggest that CRM1, present initially in an inactive form, becomes functional before the initiation of the neurula stage during gastrula-neurula transition, a period known to correspond to a critical transition in the pattern of gene expression. Finally, we confirmed the gastrula-neurula transition-dependent activation of CRM1 by pull-down experiments as well as by the study of the intracellular localization of a green fluorescent protein tagged with a nuclear export signal motif during early development. This work showed that the regulated activity of CRM1 controls specific transitions during normal development and thus might be a key regulator of early embryogenesis.

Geraniin down regulates gamma radiation-induced apoptosis by suppressing DNA damage

2013 ◽  
Vol 57 ◽  
pp. 147-153 ◽  
Author(s):  
So Jin Bing ◽  
Danbee Ha ◽  
Min Ju Kim ◽  
Eunjin Park ◽  
Ginnae Ahn ◽  
...  
Keyword(s):  
Dna Damage ◽  
Gamma Radiation ◽  
Radiation Induced ◽  
Induced Apoptosis

scholarly journals Exportin 1 Mediates Nuclear Export of the Kinetoplastid Spliced Leader RNA

2003 ◽  
Vol 2 (2) ◽  
pp. 222-230 ◽  
Author(s):  
Gusti M. Zeiner ◽  
Nancy R. Sturm ◽  
David A. Campbell
Keyword(s):  
Nuclear Export ◽  
Ectopic Expression ◽  
Specific Inhibitor ◽  
Leptomycin B ◽  
Spliced Leader ◽  
Small Nuclear Rnas ◽  
Rna Biogenesis ◽  
Common Substrate ◽  
The Common

ABSTRACT The kinetoplastid protozoan spliced leader (SL) RNA is the common substrate pre-mRNA utilized in all trans-splicing reactions. Here we show by fluorescence in situ hybridization that the SL RNA is present in the cytoplasm of Leishmania tarentolae and Trypanosoma brucei. Treatment with the karyopherin-specific inhibitor leptomycin B was toxic to T. brucei and eliminated the cytoplasmic SL RNA, suggesting that cytoplasmic SL RNA was dependent on the nuclear exporter exportin 1 (XPO1). Ectopic expression of xpo1 with a C506S mutation in T. brucei conferred resistance to leptomycin B. A reduction in SL RNA 3′ extension removal and 5′ methylation of nucleotide U4 was observed in wild-type T. brucei treated with leptomycin B, suggesting that the cytoplasmic stage is necessary for SL RNA biogenesis. This study demonstrates spatial and mechanistic similarities between the posttranscriptional trafficking of the kinetoplastid protozoan SL RNA and the metazoan cis-spliceosomal small nuclear RNAs.

Modification of radiation-induced apoptosis in radiation- or hyperthermia-adapted human lymphocytes

1994 ◽  
Vol 72 (11-12) ◽  
pp. 475-482 ◽  
Author(s):  
S. P. Cregan ◽  
D. R. Boreham ◽  
P. R. Walker ◽  
D. L. Brown ◽  
R. E. J. Mitchel
Keyword(s):  
Dna Damage ◽  
Ionizing Radiation ◽  
Adaptive Response ◽  
Human Peripheral Blood ◽  
Human Lymphocytes ◽  
Fluorescence Analysis ◽  
Terminal Deoxynucleotidyl Transferase ◽  
Protective Mechanism ◽  
Radiation Induced ◽  
Induced Apoptosis

We have investigated the influence of the cellular adaptive response to ionizing radiation on radiation-induced apoptosis in human cells. The adaptive response is believed to be a protective mechanism that confers resistance to the detrimental effects of ionizing radiation and that can be induced by different agents, including hyperthermia and radiation. We have used fluorescence analysis of DNA unwinding (FADU) to assay the induction of apoptosis in human peripheral blood lymphocytes by ionizing radiation. Using the FADU assay, we have observed the initial radiation-induced DNA damage, its subsequent disappearance due to enzymatic repair, and its time- and dose-dependent reappearance. We believe this reappearance of DNA damage to be indicative of the DNA fragmentation event associated with apoptosis. This interpretation has been supported at the individual cell level using an in situ terminal deoxynucleotidyl transferase (TDT) assay (Apoptag, Oncor Inc.), which detects the 3′-hydroxyl ends of fragmented DNA, and by fluorescence analysis of nuclear morphology in Hoechst 33258 stained cells. Pretreatment of cells with low-dose γ-radiation (0.1 Gy) or mild hyperthermia (40 °C for 30 min) altered the extent of radiation-induced (3 Gy) apoptosis. Both pretreatments sensitized lymphocytes to become apoptotic after the 3-Gy radiation exposure. This sensitization may represent an adaptive response mechanism that reduces the risk that genetically damaged cells will proliferate. The ability to modify the probability of radiation-induced apoptosis may lower the cancer risk from a radiation exposure.Key words: apoptosis, adaptive response, ionizing radiation, hyperthermia.

scholarly journals α-Melanocyte-stimulating Hormone Protects from Ultraviolet Radiation-induced Apoptosis and DNA Damage

2004 ◽  
Vol 280 (7) ◽  
pp. 5795-5802 ◽  
Author(s):  
Markus Böhm ◽  
Ilka Wolff ◽  
Thomas E. Scholzen ◽  
Samantha J. Robinson ◽  
Eugene Healy ◽  
...  
Keyword(s):  
Dna Damage ◽  
Ultraviolet Radiation ◽  
Melanocyte Stimulating Hormone ◽  
Radiation Induced ◽  
Induced Apoptosis ◽  
Stimulating Hormone

scholarly journals p21-Mediated Nuclear Retention of Cyclin B1-Cdk1 in Response to Genotoxic Stress

2004 ◽  
Vol 15 (9) ◽  
pp. 3965-3976 ◽  
Author(s):  
Fabienne Baus Charrier-Savournin ◽  
Marie-Thérèse Château ◽  
Véronique Gire ◽  
John Sedivy ◽  
Jacques Piette ◽  
...  
Keyword(s):  
Dna Damage ◽  
Current Model ◽  
Human Fibroblasts ◽  
Genotoxic Stress ◽  
Cyclin B1 ◽  
Nuclear Accumulation ◽  
G2 Arrest ◽  
Nuclear Retention ◽  
Mitotic Cyclin ◽  
Normal Human

G2 arrest of cells suffering DNA damage in S phase is crucial to avoid their entry into mitosis, with the concomitant risks of oncogenic transformation. According to the current model, signals elicited by DNA damage prevent mitosis by inhibiting both activation and nuclear import of cyclin B1-Cdk1, a master mitotic regulator. We now show that normal human fibroblasts use additional mechanisms to block activation of cyclin B1-Cdk1. In these cells, exposure to nonrepairable DNA damage leads to nuclear accumulation of inactive cyclin B1-Cdk1 complexes. This nuclear retention, which strictly depends on association with endogenous p21, prevents activation of cyclin B1-Cdk1 by Cdc25 and Cdk-activating kinase as well as its recruitment to the centrosome. In p21-deficient normal human fibroblasts and immortal cell lines, cyclin B1 fails to accumulate in the nucleus and could be readily detected at the centrosome in response to DNA damage. Therefore, in normal cells, p21 exerts a dual role in mediating DNA damage-induced cell cycle arrest and exit before mitosis. In addition to blocking pRb phosphorylation, p21 directly prevents mitosis by inactivating and maintaining the inactive state of mitotic cyclin-Cdk complexes. This, with subsequent degradation of mitotic cyclins, further contributes to the establishment of a permanent G2 arrest.

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