Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:5.99.1.2 (topoisomerase)
 9,166 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Hepatocyte growth factor (scatter factor) (HGF/SF) is a pleiotrophic mediator of epithelial cell motility, morphogenesis, angiogenesis, and tumorigenesis. HGF/SF protects cells against DNA damage by a pathway from its receptor c-Met to phosphatidylinositol 3-kinase (PI3K) to c-Akt, resulting in enhanced DNA repair and decreased apoptosis. We now show that protection against the DNA-damaging agent adriamycin (ADR; topoisomerase IIalpha inhibitor) requires the Grb2-binding site of c-Met, and overexpression of the Grb2-associated binder Gab1 (a multisubstrate adapter required for epithelial morphogenesis) inhibits the ability of HGF/SF to protect MDCK epithelial cells against ADR. In contrast to Gab1 and its homolog Gab2, overexpression of c-Cb1, another multisubstrate adapter that associates with c-Met, did not affect protection. Gab1 blocked the ability of HGF/SF to cause the sustained activation of c-Akt and c-Akt signaling (FKHR phosphorylation). The Gab1 inhibition of sustained c-Akt activation and of cell protection did not require the Gab1 pleckstrin homology or SHP2 phosphatase-binding domain but did require the PI3K-binding domain. HGF/SF protection of parental MDCK cells was blocked by wortmannin, expression of PTEN, and dominant negative mutants of p85 (regulatory subunit of PI3K), Akt, and Pak1; the protection of cells overexpressing Gab1 was restored by wild-type or activated mutants of p85, Akt, and Pak1. These findings suggest that the adapter Gab1 may redirect c-Met signaling through PI3K away from a c-Akt/Pak1 cell survival pathway.
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PMID:The multisubstrate adapter Gab1 regulates hepatocyte growth factor (scatter factor)-c-Met signaling for cell survival and DNA repair. 1143 54

During macronuclear development in the ciliate Euplotes crassus, the highly repetitive, transposon-like Tec elements possess an unusual chromatin structure. We observed that the Tec element chromatin is highly resistant to salt extraction and behaves like a nuclear matrix/chromosome scaffold-associated structure. Standard matrix/scaffold extraction procedures identified two major proteins: 1) an ~140-kDa protein that seems to be topoisomerase II based on its reactivity with anti-topoisomerase II antibodies, and 2) an 85-kDa protein that we further purified by acid extraction and have shown to be a novel protein by sequence analysis of its gene. The 85-kDa protein (p85) is a developmental stage-specific protein and is located exclusively in the developing macronucleus. Immunolocalization studies of p85 show that it colocalizes with topoisomerase II in chromatin. In addition, in situ hybridization combined with immunofluorescence localization of the proteins indicates that 100% of the Tec elements colocalize with 70% of the p85, whereas no significant colocalization with a total macronuclear sequence-specific probe is observed. p85 is the first developmental stage-specific protein identified as being specifically associated with sequences undergoing elimination in E. crassus.
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PMID:Identification of a novel "chromosome scaffold" protein that associates with Tec elements undergoing en masse elimination in Euplotes crassus. 1258 55

Amonafide, a naphthalimide derivative, although selected for exploratory clinical trials for its potent anticancer activity, has long been challenged by its unpredictable side effects. In the present study, a novel amonafide analogue, M(2)-A 2-(2-(dimethylamino)ethyl)-6-(thiophene-2-ylmethylamino)-1H-benzo[de]isoquinoline-1,3(2H)-dione was ascribed to its potent effects on topoisomerase IIalpha. Moreover, our investigation indicates that M(2)-A induces G(2)/M phase growth arrest through inhibiting PI3K/Akt pathway. M(2)-A inhibits proliferation of HeLa, HL60, HCT-8, A375, MCF-7 and MRC-5 cells, especially inhibits proliferation of HL60 with an IC(50) value of 18.86 microM. M(2)-A can not only induce DNA fragmentation, but also enhance Annexin V-FITC binding of the cells. On the one hand the expression levels of protein Cyclin B1, Cdk1 changed in response to M(2)-A treatment in HL60 cells. On the other hand we observed the inhibition of NF-kappaB nuclear translocation, up-regulation of Bax and down-regulation of Bcl-2, the caspase -3, -9 activity increase in HL60 cells after treated with M(2)-A, which indicated that the mitochondrial pathway was involved in the apoptosis signal pathway. Our results showed that the phosphorylation of p85/PI3K and Akt decreased following M(2)-A treatment. In summary, M(2)-A displayed a significant anti-tumor effect through cell cycle arrest and apoptotic induction in HL60 cells, which suggested that M(2)-A might have therapeutic potential against leukaemia.
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PMID:M(2)-A induces apoptosis and G(2)-M arrest via inhibiting PI3K/Akt pathway in HL60 cells. 1943 48