Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.30.2 (endonuclease)
 18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The internucleosomal cleavage of genomic DNA is the biochemical hallmark of apoptosis. DNase gamma, a Ca(2+)/Mg(2+)-dependent endonuclease, has been suggested to be one of the apoptotic endonucleases. We identified here 4-(4,6-dichloro-[1,3,5]-triazin-2-ylamino)-2-(6-hydroxy-3-oxo-3H-xanthen-9-yl)-benzoic acid (DR396) as a novel and potent DNase gamma inhibitor using stable HeLa S3 transfectants of DNase gamma (HeLa-gamma cells). DR396 inhibited apoptotic DNA fragmentation in HeLa-gamma cells induced by staurosporine (STS) and in rat splenocytes exposed to gamma-ray irradiation in a dose-dependent manner. This compound potently and selectively inhibited DNase gamma activity with an IC(50) value of 3.2 microM. DR396 did not delay the apoptotic processes as judged by the morphological changes and the cleavage of a death substrate, poly(ADP-ribose) polymerase (PARP). Furthermore, the compound did not prevent apoptotic DNA fragmentation in Jurkat cells induced by anti-Fas antibody (Ab), which is catalyzed by caspase-activated DNase (CAD). These findings clearly indicate that DR396 exerts chemical knockdown effect of DNase gamma on cells, suggesting that the compound could be an attractive tool for understanding of the physiological significance of DNase gamma.
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PMID:A novel inhibitor that protects apoptotic DNA fragmentation catalyzed by DNase gamma. 1555 67

Many agents successfully used in cancer chemotherapy either directly or indirectly covalently modify DNA. Examples include cisplatin, which forms a covalent adduct with guanines, and doxorubicin, which traps a cleavage intermediate between topoisomerase II and torsionally strained DNA. In most cases, the efficacy of these drugs depends on the efficiency and specificity of their DNA binding, as well as the discrimination between normal and neoplastic cells in their handling of the drug-DNA adducts. While much is known about the chemistry of drug-DNA adducts, little is known regarding the overall specificity of their formation, especially in the context of a whole human genome, where potentially billions of binding sites are possible. We used the combinatorial selection method restriction endonuclease protection, selection, and amplification (REPSA) to determine the DNA-binding specificity of the semisynthetic covalent DNA-binding polyamide tallimustine, which contains a benzoic acid nitrogen mustard appended to the minor groove DNA-binding natural product distamycin A. After investigating over 134 million possible sequences, we found that the highest affinity tallimustine binding sites contained one of two consensus sequences, either the expected distamycin hexamer binding sites followed by a CG base pair (e.g., 5'-TTTTTTC-3' and 5'-AAATTTC-3') or the unexpected sequence 5'-TAGAAC-3'. Curiously, we found that tallimustine preferentially alkylated the N7 position of guanines located on the periphery of these consensus sequences. These findings suggested a cooperative binding model for tallimustine in which one molecule noncovalently resides in the DNA minor groove and locally perturbs the DNA structure, thereby facilitating alkylation by a second tallimustine of an exposed guanine on another side of the DNA.
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PMID:Combinatorial identification of a novel consensus sequence for the covalent DNA-binding polyamide tallimustine. 1570 63

Renal cell carcinoma is the most common neoplasm occurring in the kidney and is largely resistant to current chemotherapy. Understanding the mechanisms involved in renal carcinoma cell death may lead to novel and more effective therapies. In Cak(i)-1 renal cancer cells, using phosphatidylserine externalization as a marker of apoptosis, the anti-cancer drugs 5-fluorouracil (5-FU), and its pro-drugs, doxifluridine (Dox) and floxuridine (Flox) proceeds via a caspase-dependent mechanism. In contrast, phosphatidylserine externalization produced by staurosporine in the renal cancer cell lines Cak(i)-1 and A-498 proceeds via a caspase-independent mechanism. That is, the pan caspase inhibitor N-benzyloxycabonyl-Val-Ala-Asp-fluoromethylketone (ZVAD) did not ameliorate annexin V binding, cell shrinkage or changes in nuclear morphology. Subsequent experiments were conducted to determine mediators of phosphatidylserine externalization, using annexin V binding, when caspases were inhibited. Prior treatment of A-498 cells with cathepsin B (CA74 methyl ester), cathespsin D (pepstatin A) or calpain inhibitors (calpeptin, E64d) in the presence or absence of ZVAD did not ameliorate annexin V binding. The endonuclease inhibitor aurintricarboxylic acid (ATA), phospholipase A(2) inhibitor bromoenol lactone (BEL), protein synthesis inhibitor cycloheximide (CH) and chloride channel blockers niflumic acid (NFA) and 5-nitro-2-(3-phenylpropylamino) benzoic acid (NPPB) all had no effect on staurosporine-induced annexin V binding in A-498 cells either in the presence or absence of ZVAD. We also modulated sphingomyelin and the de novo pathways of ceramide synthesis and found no amelioration of staurosporine-induced annexin V binding in A-498 cells either in the presence or absence of ZVAD. These results indicate that 5-FU, Dox and Flox induce externalization of phosphatidylserine during apoptosis in Cak(i)-1 renal cancer cells primarily through a caspase-dependent mechanism and that externalization of phosphatidylserine during apoptosis produced by staurosporine in the renal cancer cell line A-498 is independent of many of the common signaling pathways known to be involved in this process.
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PMID:Caspase-dependent and -independent induction of phosphatidylserine externalization during apoptosis in human renal carcinoma Cak(1)-1 and A-498 cells. 1709 91