A Novel Nuclear Localization Signal in Human DNA Topoisomerase I

Mo, Yin Yuan; Wang, Chengyi; Beck, William T.

doi:10.1074/jbc.m003135200

Cited by 49 publications

(56 citation statements)

References 45 publications

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“…In addition, the K117R mutant showed essentially the same CPT sensitivity as wildtype Topo1, in agreement with the fact that CPT binds to Topo1 near the active site of the C-terminal domain (Pommier et al, 1995;Stewart et al, 1998). Meanwhile, the N-terminal domain, containing four NLS sequences, is important for Topo1 to localize in the nucleus and functioning in vivo (Mo et al, 2000a;Stewart et al, 1996aStewart et al, ,b, 1997. The K117R and K153R Figure 4 DNA relaxation activities and CPT sensitivities of WT and K117R Topo1.…”

Section: Discussionsupporting

confidence: 56%

SUMO-1 conjugation to intact DNA topoisomerase I amplifies cleavable complex formation induced by camptothecin

et al. 2002

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Section: Discussionsupporting

confidence: 56%

SUMO-1 conjugation to intact DNA topoisomerase I amplifies cleavable complex formation induced by camptothecin

et al. 2002

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“…1) ) were emphasized as its NLS. Because the BD does not contain a classic NLS, the nuclear localization of GSK-3β seems to be not mediated by importin α (Mo et al, 2000;Takeda et al, 2000). We assumed that these two basic sequences are the part of PY-NLS.…”

mentioning

confidence: 99%

The Nuclear Localization of Glycogen Synthase Kinase 3β Is Required Its Putative PY-Nuclear Localization Sequences

Sein

Lee

Chun

et al. 2012

Molecules and Cells

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Glycogen synthase kinase-3β(GSK-3β), which is a member of the serine/threonine kinase family, has been shown to be crucial for cellular survival, differentiation, and metabolism. Here, we present evidence that GSK-3β is associated with the karyopherin β2 (Kap β2) (102-kDa), which functions as a substrate for transportation into the nucleus. A potential PY-NLS motif ( 109 IVRLRYFFY 117) was observed, which is similar with the consensus PY NLS motif (R/K/H)X 2-5 PY in the GSK-3β catalytic domain. Using a pull down approach, we observed that GSK-3β physically interacts with Kap β2 both in vivo and in vitro. Secondly, GSK-3β and Kap β2 were shown to be co-localized by confocal microscopy. The localization of GSK-3β to the nuclear region was disrupted by putative Kap β2 binding site mutation. Furthermore, in transient transfection assays, the Kap β2 binding site mutant induced a substantial reduction in the in vivo serine/threonine phosphorylation of GSK-3β, where-as the GSK-3β wild type did not. Thus, our observations indicated that Kap β2 imports GSK-3β through its putative PY NLS motif from the cytoplasm to the nucleus and increases its kinase activity.

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“…whether caspase-mediated cleavage of Top1 contributes to or results from Top1cc formation. Prior studies have shown that cleavage of Top1 to the 80-kDa form does not prevent its nuclear localization (38) and that 80-kDa Top1 retains its ability to form Top1cc in cells exposed to camptothecin (7). In vitro experiments have further demonstrated that truncated 68-kDa C-terminal recombinant Top1 is still catalytically active (37).…”

Section: Caspase-3-cleaved Top1 Is Preferentially Involved In the Apomentioning

confidence: 99%

“…Caspase-3 cleaves Top1 after aspartate residue 146 and generates an 80-kDa C-terminal fragment (Fig. 4A) that remains capable of forming Top1cc (7, 37) and still possesses one functional nuclear localization signal (38) (Fig. 4A).…”

Section: Top1 Induces Apoptotic Nuclear Fissionmentioning

confidence: 99%

Topoisomerase I Requirement for Death Receptor-induced Apoptotic Nuclear Fission

Sordet

Goldman

Redon

et al. 2008

Journal of Biological Chemistry

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Topoisomerase I (Top1) is known to relax DNA supercoiling generated by transcription, replication, and chromatin remodeling. However, it can be trapped on DNA as cleavage complexes (Top1cc) by oxidative and carcinogenic DNA lesions, base damage, and camptothecin treatment. We show here that Top1 is also functionally involved in death receptor-induced programmed cell death. In cells exposed to TRAIL or Fas ligand, Top1cc form at the onset of apoptosis. Those apoptotic Top1cc are prevented by caspase inhibition and Bax inactivation, indicating that both caspases and the mitochondrial death pathway are required for their formation. Accordingly, direct activation of the mitochondrial pathway by BH3 mimetic molecules induces apoptotic Top1cc. We also show that TRAIL-induced apoptotic Top1cc are preferentially formed by caspase-3-cleaved Top1 at sites of oxidative DNA lesions with an average of one apoptotic Top1cc/100 kbp. Examination of Top1 knockdown cells treated with TRAIL revealed similar DNA fragmentation but a marked decrease in apoptotic nuclear fission with reduced formation of nuclear bodies. Thus, we propose that Top1 contributes to the full apoptotic responses induced by TRAIL.Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) 2 is a promising therapeutic agent because it induces apoptosis in a wide variety of cancer cells without affecting normal tissues (1, 2). TRAIL belongs to the TNF family of cytokines, including TNF␣ and Fas ligand, which induce apoptosis by binding to their cognate plasma membrane receptors (3). The binding of TRAIL to the DR4 or DR5 receptors and the binding of Fas ligand to Fas receptor cause the intracellular death domains of those receptors to trimerize, which leads to the recruitment of FADD and the activation of caspase-8. Caspase-8 then cleaves and thereby activates caspase-3 either directly (type I cells) or/and indirectly (type II cells) (4) by activating the mitochondrial death pathway through the cleavage of Bid (5). Cleaved Bid binds to and activates the pro-apoptotic Bcl-2 relatives Bax and Bak proteins, causing the release of mitochondrial cytochrome c and the activation of caspase-9 and caspase-3 (6). Activated caspase-3 (and other downstream caspases) cleaves a broad array of intracellular targets including DNA topoisomerase I (Top1) (7). It is also required to induce the controlled rearrangement and degradation of nuclear structures with chromatin condensation, DNA fragmentation, nuclear fission, and release of apoptotic nuclear bodies in the extracellular space (8). TRAIL-induced apoptosis also involves an accumulation of intracellular reactive oxygen species (ROS) (9).Top1 removes DNA superhelical tensions generated during transcription, replication, and chromatin remodeling (10) and is essential in higher eukaryotes (11). It relaxes DNA by forming transient DNA single-strand breaks that are produced as Top1 forms a covalent bond between its active site tyrosine (Tyr 723 ) and a 3Ј-DNA phosphate. These Top1 cleavage complexes (Top1cc) allow con...

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A Novel Nuclear Localization Signal in Human DNA Topoisomerase I

Cited by 49 publications

References 45 publications

SUMO-1 conjugation to intact DNA topoisomerase I amplifies cleavable complex formation induced by camptothecin

SUMO-1 conjugation to intact DNA topoisomerase I amplifies cleavable complex formation induced by camptothecin

The Nuclear Localization of Glycogen Synthase Kinase 3β Is Required Its Putative PY-Nuclear Localization Sequences

Topoisomerase I Requirement for Death Receptor-induced Apoptotic Nuclear Fission

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