In this study, we investigated autophagy induced in HeLa cells by copper(II) complex of ethyl 2-[bis(2-pyridylmethyl)amino] propionate ligand (ETDPA) (formula: [(ETDPA)Cu(phen)](ClO4)2 (abbreviated as LCu),a novel synthetic copper(II) complex whose DNA binding activity has been proved. Cell viability, autophagic levels and generation of ROS were evaluated following the exposure to LCu. LCu-induced cell death in a dose- and time-dependent manner, which was demonstrated by enhanced fluorescence intensity of monodansylcadervarine (MDC), as well as elevated expression of autophagy-related protein MAP-LC3. These phenomena were all attenuated after pretreatment with autophagy inhibitors 3-MA or NH(4)Cl. Furthermore, our data indicated that LCu-triggered autophagy through ROS: cellular ROS levels were increased after LCu treatment, which was reversed by ROS scavenger NAC (N-acetylcysteine). As a consequence, Lcu-mediated autophagy was partly blocked by NAC. In summary, we synthesized a novel copper(II) complex and showed that this compound was effective in killing HeLa cells via ROS-triggered autophagic pathway.
"These results suggest that different apoptosis pathways may be activated by Cu exposure, also suggesting the existence of crosstalk interactions between them. A schematic representation of hypothetical Cu apoptosis pathways activation, based on the present results and the current knowledge, is presented in Fig. 4. The Cu toxicity is attributed, at least in part, to its ability to induce ROS formation (Bopp et al., 2008; Sandrini et al., 2009; Guo et al., 2010) which, in turn, has previously been associated with the activation of p53 (Li et al., 1998; Ostrakhovitch and Cherian, 2005; Tassabehji et al., 2005). In fact, the early increase in mRNA expression of p53 gene, observed in the present study, is suggestive of its involvement in apoptosis activation, since TUNEL-positive cells became more evident soon after 6 h of Cu exposure (Fig. 4-Box 1). "
[Show abstract][Hide abstract] ABSTRACT: Copper (Cu) is an essential micronutrient that, when present in high concentrations, becomes toxic to aquatic organisms. It is known that Cu toxicity may induce apoptotic cell death. However, the precise mechanism and the pathways that are activated, in fish, are still unclear. Thus, this study aimed to assess which apoptotic pathways are triggered by Cu, in zebrafish (Danio rerio) gill, the main target of waterborne pollutants. Fish where exposed to 12.5 and 100μg/L of Cu during 6, 12, 24 and 48h. Fish gills were collected to TUNEL assay and mRNA expression analysis of selected genes by real time PCR. An approach to different apoptosis pathways was done selecting p53, caspase-8, caspase-9 and apoptosis inducing factor (AIF) genes. The higher incidence of TUNEL-positive cells, in gill epithelia of the exposed fish, proved that Cu induced apoptosis. The results suggest that different apoptosis pathways are triggered by Cu at different time points of the exposure period, as the increase in transcripts was sequential, instead of simultaneous. Apoptosis seems to be initiated via intrinsic pathway (caspase-9), through p53 activation; then followed by the extrinsic pathway (caspase-8) and finally by the caspase-independent pathway (AIF). A possible model for Cu-induce apoptosis pathways is proposed.
"O 2 and NO are considered to be the most important mediators among ROS and RNS, respectively. Free oxidative agents are known to induce autophagy and can also lead to cell death during strong and prolonged stimulation (Djavaheri-Mergny et al., 2007; Filomeni et al., 2010; Guo et al., 2010). To assess the impact of ROS/RNS production in CHIKV-induced autophagy, we rst investigated whether CHIKV infection induces ROS and/or RNS production. "
[Show abstract][Hide abstract] ABSTRACT: Autophagy is an important survival pathway and can participate in the host response to infection. Studying Chikungunya virus (CHIKV), the causative agent of a major epidemic in India, Southeast Asia, and southern Europe, we reveal a novel mechanism by which autophagy limits cell death and mortality after infection. We use biochemical studies and single cell multispectral assays to demonstrate that direct infection triggers both apoptosis and autophagy. CHIKV-induced autophagy is mediated by the independent induction of endoplasmic reticulum and oxidative stress pathways. These cellular responses delay apoptotic cell death by inducing the IRE1α-XBP-1 pathway in conjunction with ROS-mediated mTOR inhibition. Silencing of autophagy genes resulted in enhanced intrinsic and extrinsic apoptosis, favoring viral propagation in cultured cells. Providing in vivo evidence for the relevance of our findings, Atg16L(HM) mice, which display reduced levels of autophagy, exhibited increased lethality and showed a higher sensitivity to CHIKV-induced apoptosis. Based on kinetic studies and the observation that features of apoptosis and autophagy were mutually exclusive, we conclude that autophagy inhibits caspase-dependent cell death but is ultimately overwhelmed by viral replication. Our study suggests that inducers of autophagy may limit the pathogenesis of acute Chikungunya disease.
Journal of Experimental Medicine 04/2012; 209(5):1029-47. DOI:10.1084/jem.20110996 · 12.52 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Autophagy is a catalytic process of the bulk degradation of long-lived cellular components, ultimately resulting in lysosomal digestion within mature cytoplasmic compartments known as autophagolysosomes. Autophagy serves many functions in the cell, including maintaining cellular homeostasis, a means of cell survival during stress (e.g., nutrient deprivation or starvation) or conversely as a mechanism for cell death. Increased reactive oxygen species (ROS) production and the resulting oxidative cell stress that occurs in many disease states has been shown to induce autophagy. The following review focuses on the roles that autophagy plays in response to the ROS generated in several diseases.
Oxidative Medicine and Cellular Longevity 03/2010; 3(3):168-77. DOI:10.4161/oxim.3.3.12106 · 3.36 Impact Factor
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