EndoG links Bnip3-induced mitochondrial damage and caspase-independent DNA fragmentation in ischemic cardiomyocytes

Mitochondrial dysfunction, caspase activation and caspase-dependent DNA fragmentation are involved in cell damage in many tissues. However, differentiated cardiomyocytes repress the expression of the canonical apoptotic pathway and their death during ischemia is caspase-independent. The atypical BH3-only protein Bnip3 is involved in the process leading to caspase-independent DNA fragmentation in cardiomyocytes. However, the pathway by which DNA degradation ensues following Bnip3 activation is not resolved. To identify the mechanism involved, we analyzed the interdependence of Bnip3, Nix and EndoG in mitochondrial damage and DNA fragmentation during experimental ischemia in neonatal rat ventricular cardiomyocytes. Our results show that the expression of EndoG and Bnip3 increases in the heart throughout development, while the caspase-dependent machinery is silenced. TUNEL-positive DNA damage, which depends on caspase activity in other cells, is caspase-independent in ischemic cardiomyocytes and ischemia-induced DNA high and low molecular weight fragmentation is blocked by repressing EndoG expression. Ischemia-induced EndoG translocation and DNA degradation are prevented by silencing the expression of Bnip3, but not Nix, or by overexpressing Bcl-xL. These data establish a link between Bnip3 and EndoG-dependent, TUNEL-positive, DNA fragmentation in ischemic cardiomyocytes in the absence of caspases, defining an alternative cell death pathway in postmitotic cells.

The activity of the anti-apoptotic fragment generated by the caspase-3/p120 RasGAP stress-sensing module displays strict Akt isoform specificity.

The caspase-3/p120 RasGAP module acts as a stress sensor that promotes pro-survival or pro-death signaling depending on the intensity and the duration of the stressful stimuli. Partial cleavage of p120 RasGAP generates a fragment, called fragment N, which protects stressed cells by activating Akt signaling. Akt family members regulate many cellular processes including proliferation, inhibition of apoptosis and metabolism. These cellular processes are regulated by three distinct Akt isoforms: Akt1, Akt2 and Akt3. However, which of these isoforms are required for fragment N mediated protection have not been defined. In this study, we investigated the individual contribution of each isoform in fragment N-mediated cell protection against Fas ligand induced cell death. To this end, DLD1 and HCT116 isogenic cell lines lacking specific Akt isoforms were used. It was found that fragment N could activate Akt1 and Akt2 but that only the former could mediate the protective activity of the RasGAP-derived fragment. Even overexpression of Akt2 or Akt3 could not rescue the inability of fragment N to protect cells lacking Akt1. These results demonstrate a strict Akt isoform requirement for the anti-apoptotic activity of fragment N.

Pyroptosis: Caspase-11 Unlocks the Gates of Death.

How inflammatory caspases trigger pyroptotic cell death is mostly unexplained. In this issue of Immunity, Núñez and colleagues report that caspase-11 cleaves the transmembrane channel pannexin-1, causing an efflux of cellular ATP that promotes a P2X7 receptor-dependent pyroptosis.

Expressão citofotométrica quantitativa da CASPASE-3 e do CD-34 no carcinoma ductal infiltrante de mama

OBJETIVO: Descrever, correlacionar e comparar a expressão dos marcadores tumorais CD-34 (angiogênese) e caspase-3 (apoptose) em carcinoma ductal invasor de mama. MÉTODOS: Foram utilizados 22 casos de adenocarcinoma infiltrante de mama provenientes de blocos de parafina e, após preparo específico para imunoistoquímica, 15 apresentaram leitura satisfatória e foram avaliados pelo sistema de fotocitometria de imagem SAMBA 4000® e software IMMUNO®. Os parâmetros analisados foram o índice de marcagem e densidade óptica. RESULTADOS: Para o CD-34 não houve normalidade dos dados na análise do índice de marcagem, com obtenção de P=0,019, havendo normalidade para a análise da densidade óptica, com P=0,199. Para a caspase-3 houve normalidade de dados para o índice marcagem com P=0,306 e para a densidade óptica com P=0,114; não houve diferença estatística significativa entre eles em relação à média do índice de marcagem (P=0,872) e da densidade óptica (P=0,816), quando analisados os parâmetros que definem a expressão dos marcadores; existiu tendência à associação entre a densidade óptica e o índice de marcagem do marcador tumoral caspase-3, com P=0,025. Não foi observada tendência à associação quando comparados densidade óptica e índice de marcagem do marcador tumoral CD-34; índice de marcagem do marcador tumoral caspase-3 e índice de marcagem do marcador tumoral CD-34; e densidade óptica da caspase-3 com a do CD-34. CONCLUSÃO: Dos 22 casos incluídos foi possível verificar a expressão do marcador CD-34 em 18 lâminas e da caspase-3 em 22 lâminas; Para o CD-34 não houve normalidade dos dados na análise do índice de marcagem, havendo sim normalidade para a análise da densidade óptica. Para a caspase-3 houve normalidade de dados tanto para o índice de marcagem como para a densidade óptica. Existe tendência à associação entre a densidade óptica e o índice de marcagem da caspase-3. Não foi observada tendência quando comparados densidade óptica e índice de marcagem no CD-34.

Expressão citofotométrica da Caspase-3 no carcinoma papilífero da tireóide e no bócio colóide

OBJETIVO: Descrever a expressão citofotométrica quantitativa do marcador caspase-3 no bócio colóide e no carcinoma papilífero da tireóide e comparar a imunoexpessão entre as doenças. MÉTODOS: Realizou-se estudo imunoistoquímico da proteína caspase-3 em 17 blocos de parafina de carcinoma papilífero da tiróide e 20 de bócio colóide, através do sistema SAMBA 4000 - (Sistema de análise microscópica de busca automática), objetivando-se analisar duas variáveis: índice de marcagem e densidade óptica. RESULTADOS: Houve diferença significativa quanto ao índice de marcagem da caspase-3, entre o bócio colóide e o carcinoma papilífero, sendo maior no carcinoma, e não foi encontrada diferença significativa quanto à densidade óptica. Para o bócio colóide, o coeficiente de correlação estimado entre o índice de marcagem e a densidade óptica foi igual a 0,72, indicando assim, a rejeição da hipótese nula (p <0,001), afirmando-se que existe associação positiva e significativa entre o índice de marcagem e a densidade óptica da caspase-3. Para o carcinoma papilífero da tiróide, o coeficiente de correlação estimado entre o índice de marcagem e a densidade óptica 3 foi de 0,34. O resultado do teste estatístico indicou que não se pode afirmar que existe associação entre esses parâmetros. CONCLUSÃO: Para o bócio colóide existe associação positiva e significativa entre as duas variáveis, índice de marcagem e a densidade óptica da caspase-3, enquanto que para o carcinoma papilífero não existe essa associação. O estudo comparativo entre a análise quantitativa da caspase-3, demonstrou que a apoptose é mais evidente no carcinoma papilífero do que no bócio colóide.

Antioxidant dietary deficiency induces caspase activation in chick skeletal muscle cells

Apoptosis and necrosis are two distinct forms of cell death that can occur in response to different agents and stress conditions. In order to verify if the oxidative stress induced by dietary selenium and vitamin E deficiencies can lead muscle cells to apoptosis, one-day-old chicks were reared using diets differing in their vitamin E (0 or 10 IU/kg) and selenium (0 or 0.15 ppm) supplementation. Chick skeletal muscle tissue was obtained from 28-day-old animals and used to verify apoptosis occurrence based on caspase activity detection and DNA fragmentation. Antioxidant deficiency significantly increased caspase-like activity assessed by the hydrolysis of fluorogenic peptide substrates (Abz-peptidyl-EDDnp) at lambdaexc = 320 nm and lambdaem = 420 nm. Proteolytic activation was not accompanied by typical internucleosomal DNA fragmentation detected by field inversion gel electrophoresis. Although the general caspase inhibitor N-benzyloxycarbonyl-Val-Ala-Asp(O-Me) fluoromethyl ketone (Z-VAD-fmk) (0 to 80 muM) did not block caspase-like activity when preincubated for 30 min with muscle homogenates, the hydrolyzed substrates presented the same cleavage profile in HPLC (at the aspartic acid residue) when incubated with the purified recombinant enzyme caspase-3. These data indicate that oxidative stress causes caspase-like activation in muscle cells and suggest that cell death associated with exudative diathesis (dietary deficiency of selenium and vitamin E) can follow the apoptotic pathway.

Caspase-8 and p38MAPK in DATS-induced apoptosis of human CNE2 cells

Nasopharyngeal carcinoma is a common malignancy in Southern China of uncertain etiologic origin. Diallyl trisulfide (DATS), one of the major components of garlic (Allium sativum), is highly bactericidal and fungicidal. In this study, we investigated the function of p38 mitogen-activated protein kinase (MAPK) and caspase-8 in DATS-induced apoptosis of human CNE2 cells using MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide], flow cytometry assay, and Western blotting. After CNE2 cells were treated with DATS (50, 100, or 150 μM) for 24 h, cell viability rates were 75.9, 63.4 and 39.6%, and apoptosis rates were 24.5, 36.9, and 62.4%, respectively. The data showed that DATS induced CNE2 cell death in a dose-dependent manner. After human CNE2 cells were treated with 100 μM DATS and inhibitors (10 μM SB203580 and Z-LETD-FMK for p38MAPK and caspase-8, respectively), changes in cell viability and apoptosis and in p38MAPK and caspase-8 activity were detected. Cell viability rates were 66.5 and 68.1% and decreased 9.9 and 11.5% compared with inhibitor treatment alone. Apoptosis rates were 31.53 and 29.98% and increased 9.1 and 10% compared with inhibitor treatment alone. The results indicated that DATS activates p38MAPK and caspase-8, but both inhibitors have an effect on P38MAPK and caspase-8 activity. In conclusion, our data indicate that p38MAPK and caspase-8 are involved in the process of DATS-induced apoptosis in human CNE2 cells and interact with each other.

Caspase dependence of the death of neonatal retinal ganglion cells induced by axon damage and induction of autophagy as a survival mechanism

We examined the degeneration of post-mitotic ganglion cells in ex-vivo neonatal retinal explants following axon damage. Ultrastructural features of both apoptosis and autophagy were detected. Degenerating cells reacted with antibodies specific for activated caspase-3 or -9, consistent with the presence of caspase activity. Furthermore, peptidic inhibitors of caspase-9, -6 or -3 prevented cell death (100 µM Ac-LEDH-CHO, 50 µM Ac-VEID-CHO and 10 µM Z-DEVD-fmk, respectively). Interestingly, inhibition of autophagy by 7-10 mM 3-methyl-adenine increased the rate of cell death. Immunohistochemistry data, caspase activation and caspase inhibition data suggest that axotomy of neonatal retinal ganglion cells triggers the intrinsic apoptotic pathway, which, in turn, is counteracted by a pro-survival autophagic response, demonstrated by electron microscopy profiles and pharmacological autophagy inhibitor.

Aqueous peroxyl radical exposure to THP-1 cells causes glutathione loss followed by protein oxidation and cell death without increased caspase-3 activity

Protein oxidation within cells exposed to oxidative free radicals has been reported to occur in an uninhibited manner with both hydroxyl and peroxyl radicals. In contrast, THP-1 cells exposed to peroxyl radicals (ROO center dot) generated by thermo decomposition of the azo compound AAPH showed a distinct lag phase of at least 6 h, during which time no protein oxidation or cell death was observed. Glutathione appears to be the source of the lag phase as cellular levels were observed to rapidly decrease during this period. Removal of glutathione with buthionine sulfoxamine eliminated the lag phase. At the end of the lag phase there was a rapid loss of cellular MTT reducing activity and the appearance of large numbers of propidium iodide/annexin-V staining necrotic cells with only 10% of the cells appearing apoptotic (annexin-V staining only). Cytochrome c was released into the cytoplasm after 12 h of incubation but no increase in caspase-3 activity was found at any time points. We propose that the rapid loss of glutathione caused by the AAPH peroxyl radicals resulted in the loss of caspase activity and the initiation of protein oxidation. The lack of caspase-3 activity appears to have caused the cells to undergo necrosis in response to protein oxidation and other cellular damage. (c) 2007 Elsevier B.V. All rights reserved.

Substituted titanocenes induce caspase-dependent apoptosis in human epidermoid carcinoma cells in vitro and exhibit antitumour activity in vivo

Titanocene compounds are a novel series of agents that exhibit cytotoxic effects in a variety of human cancer cells in vitro and in vivo. In this study, the antiproliferative activity of two titanocenes (Titanocenes X and Y) was evaluated in human epidermoid cancer cells in vitro. Titanocenes X and Y induce apoptotic cell death in epidermoid cancer cells, with IC50 values that are comparable to cisplatin. Characterisation of the cell death pathway induced by titanocene compounds in A431 cells revealed that apoptosis is preceded by cell cycle arrest and the inhibition of cell proliferation. The induction of apoptosis is dependent on the activation of caspase-3 and -7 but not caspase-8. Furthermore, the antitumour activity of Titanocene Y was tested in an A431 xenograft model of epidermoid cancer. Results indicate that Titanocene Y significantly reduced the growth of A431 xenografts with an antitumour effect similar to cisplatin. These results suggest that titanocenes represent a novel series of promising antitumour agents.

Altered Ex Vivo Expression of Caspase 8, Caspase 9, and Bcl-2 Is Associated with T-Cell Hyporeactivity in Patients with Paracoccidioidomycosis

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Human bcl-2 expression, cleaved caspase-3, and KSHV LANA-1 in Kaposi sarcoma lesions

We aimed to evaluate the frequency of Kaposi sarcoma (KS)-associated herpesvirus (KSHV) infection in KS lesions in patients from Brazil. In addition, expression of human bcl-2, cleaved caspase-3, and KSHV latency-associated nuclear antigen (LANA)-1 in tumors was evaluated using inummohistochemical analysis. We studied 64 KS cases, classified as follows: classical, 20 (31 %); iatrogenic, 2 (3 %); AIDS-associated, 25 (39%); and not otherwise specified (lack of information about HIV status), 17 (27%). KSHV was detected by polymerase chain reaction (PCR) in 61 cases (95%); 40 cases (63%) were KSHV+ by PCR and immunohistochemical analysis for LANA-L Immunoexpression of bcl-2 was detected in 47 cases (73%). Only a few cells in 15 cases (23%) of KS had demonstrable immunostaining for cleaved caspase-3. These results further support the association of KSHV with all KS forms. Cleaved caspase-3 in KS tumors was infrequent, which may reflect the inhibition of apoptosis owing to bcl-2 overexpression observed in the majority of KS tumors.

Canine corpus luteum regression: Apoptosis and caspase-3 activity

The present study evaluated the occurrence of apoptosis and caspase-3 activity in the canine corpus luteum during the period of luteal regression in eight pregnant and nine nonpregnant diestrus bitches. Intact luteal cells were obtained from corpora lutea in both peripartum pregnant bitches and nonpregnant diestrus bitches at approximately 65 d (range 63-68) after estrus, but not at days 75 and 85 in nonpregnant bitches. In all bitches, apoptotic cells were rarely detected and when present, those cells were more easily detected using the hematoxylin and eosin technique than using the critical electrolyte concentration technique. The luteal structures at 75 and 85 d of diestrus had histological characteristics similar to a corpus albicans. Caspase-3 activity was detected in morphologically normal corpora lutea from both pregnant and diestrus bitches around day 65, and also in the later structures considered corpus albicans tissue. These results suggested that apoptosis may not be the major mechanism involved in canine functional luteal regression, and that caspase-3 participated in both functional and morphological luteolysis and in the tissue reorganization involved in corpus albicans formation. (c) 2006 Published by Elsevier B.V.

Relação da ciclooxigenase-2 com VEGF e a caspase-3 nas neoplasias mamárias de cadelas

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)