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1.
Experimental & Molecular Medicine ; : 435-444, 2006.
Artículo en Inglés | WPRIM | ID: wpr-200505

RESUMEN

Cardiotoxin III (CTX III), a basic polypeptide with 60 amino acid residues isolated from Naja naja atra venom, has been reported to have anticancer activity. CTX III-induced K562 cell apoptosis was confirmed by DNA fragmentation (DNA ladder, sub-G1 formation) and phosphatidylserine (PS) externalization with an IC50 value of 1.7 mug/ml at 48 h. A mechanistic analysis demonstrated that CTX III-induced apoptotic cell death was accompanied by up-regulation of both Bax and endonuclease G (Endo G), and downregulation of Bcl-X(L). CTX III had no effect on the levels of Bcl-2, Bid, XIAP survivin, and AIF proteins. CTX III treatment caused loss of the mitochondrial membrane potential (delta psi m), release of mitochondrial cytochrome c to the cytosol, and activation of both caspase-9 and -3. CTX III-induced apoptosis was significantly blocked by the broad-spectrum caspase inhibitor Z-VAD-FMK. However, CTX III did not generate reactive oxygen species (ROS) and antioxidants, including N-acetylcysteine and catalase, did not block CTX III-induced apoptosis in K562 cells. Modulation of Bax, Bcl-X(L), and the Endo G proteins, release of mitochondrial cytochome c, and activation of caspase-3 and -9 all are involved in the CTX III-triggered apoptotic process in human leukemia K562 cells.


Asunto(s)
Humanos , Proteína bcl-X/metabolismo , Proteína X Asociada a bcl-2/metabolismo , Regulación hacia Arriba/efectos de los fármacos , Especies Reactivas de Oxígeno/metabolismo , Proteínas Mitocondriales/metabolismo , Membranas Mitocondriales/efectos de los fármacos , Potenciales de la Membrana/efectos de los fármacos , Células K562 , Proteínas Inhibidoras de la Apoptosis/metabolismo , Endodesoxirribonucleasas/metabolismo , Regulación hacia Abajo/efectos de los fármacos , Proteínas Cardiotóxicas de Elápidos/farmacología , Citocromos c/metabolismo , Proliferación Celular/efectos de los fármacos , Caspasas/metabolismo , Apoptosis/efectos de los fármacos
2.
Indian J Exp Biol ; 2004 Aug; 42(8): 808-11
Artículo en Inglés | IMSEAR | ID: sea-63113

RESUMEN

Effect of repeated (20 days) exposure to picrotoxin (PTX) on rat liver lysosomal function was evaluated by measuring the free and total activities of acid phosphatase, cathepsin D, ribonuclease II (RNAse II) and deoxyribonuclease II (DNAse II). The free activities of the nucleases (both RNAse II and DNAse II) were increased following PTX exposure. The total DNAse II activity was increased by 2.2-fold whereas the total acid phosphatase activity was decreased by 28%. Consequently, the ratios of total activity / free activity were low in the PTX exposed groups, implying loss of membrane integrity. Cathepsin D activity was completely abolished. The results show that repeated exposure to PTX can lead to lysosomal dysfunction in liver.


Asunto(s)
Fosfatasa Ácida/metabolismo , Animales , Catepsina D/metabolismo , Convulsivantes/administración & dosificación , Endodesoxirribonucleasas/metabolismo , Exorribonucleasas/metabolismo , Inyecciones Intraperitoneales , Hígado/efectos de los fármacos , Lisosomas/efectos de los fármacos , Masculino , Picrotoxina/administración & dosificación , Ratas
3.
Indian J Exp Biol ; 1993 Aug; 31(8): 667-72
Artículo en Inglés | IMSEAR | ID: sea-63144

RESUMEN

Limited digestion (2 min) of Sarcoma-180 nuclei by DNase-II released two nonhistone proteins from the hypersensitive sites of chromatin. The apparent molecular weights of these two proteins were 34 and 21 kDa. These proteins showed a moderate but specific inhibition in in vitro cell free transcription assay with native chromatin as template as opposed to no effect on native DNA transcription.


Asunto(s)
Animales , Cromatina/metabolismo , ADN de Neoplasias/metabolismo , Proteínas de Unión al ADN/aislamiento & purificación , Endodesoxirribonucleasas/metabolismo , Masculino , Ratones , Ratas , Sarcoma 180/genética , Transcripción Genética/fisiología
4.
Indian J Biochem Biophys ; 1992 Jun; 29(3): 227-30
Artículo en Inglés | IMSEAR | ID: sea-27303

RESUMEN

The size of the repair patch produced by E. coli DNA polymerase (Pol I) following the removal of a pyrimidine dimer from DNA in response to the nicking activity of T4 endonuclease (T4 endo V) was determined. A 48-bp DNA containing a pyrimidine dimer at a defined location was labelled in the damaged strand and incubated with T4 endo V and E. coli endonuclease IV. Subsequently, DNA synthesis by DNA Pol I was carried out in the presence of four dNTPs, ATP and DNA ligase. Analysis of the reaction products on a sequencing gel revealed a ladder of only 4-oligonucleotides, 1-4 nucleotides greater in length than the fragment generated by the combined nicking activities of T4 endo V and E. coli endonuclease IV. Thus we conclude that the in vitro repair patch size of T4 endo V is 4 nucleotides and that in some cases the repaired DNA is not ligated.


Asunto(s)
Secuencia de Bases , ADN/metabolismo , ADN Polimerasa I/metabolismo , Reparación del ADN , Replicación del ADN , Desoxirribonucleasa (Dímero de Pirimidina) , Endodesoxirribonucleasas/metabolismo , Escherichia coli/enzimología , Modelos Estructurales , Datos de Secuencia Molecular , Conformación de Ácido Nucleico , Oligodesoxirribonucleótidos , Especificidad por Sustrato , Fagos T/enzimología , Proteínas Virales
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