Differential autophagic responses to nano-sized materials

Abstract

Autophagy is a complex catabolic pathway that mediates degradation of excess or unwanted cytoplasmic components through the lysosome. Activated by environmental factors, such as nutrient depletion, and intracellular stimuli, such as proteotoxic stress, it provides a highly dynamic quality control mechanism to recycle cellular components, eliminate aberrant materials, and, ultimately, maintain cellular homeostasis. A growing body of evidence suggests that autophagy is also activated upon internalization of engineered nanomaterials, most likely as a protective response to what is perceived as foreign or toxic. This review describes the mechanisms of autophagy activation in response to naturally occurring and engineered nanomaterials. We provide a comprehensive analysis of the impact of nanomaterials on the lysosome-autophagy system, with particular emphasis on cellular markers associated with biocompatible and bioadverse outcomes of autophagy activation, such as clearance of toxic material and autophagy-associated cell death. Potential applications of the next-generation nanomaterials designed to interface with cellular clearance mechanisms with precisely tunable properties are also discussed.

Near Infrared-Activated Dye-Linked ZnO Nanoparticles Release Reactive Oxygen Species for Potential Use in Photodynamic Therapy

“…The differences in lysosomal capacity and mitochondrial activity between cancerous and non-cancerous cells are additional factors that have been shown to contribute to preferential toxicity [76][77][78]. Similar results were observed in a study in which ZnO nanoparticles showed higher toxicity towards the cancer cells and minimal toxicity towards non-cancerous cells using human lung adenocarcinoma A549, human hepatocellular carcinoma HepG2, and human bronchial epithelial BEAS-2B, and two primary rat cells.…”

Toxicogenomics of Gold Nanoparticles in a Marine Fish: Linkage to Classical Biomarkers

“…Whereas for the highest AuNP concentration, an upregulation of genes linked to autophagy and endoplasmic reticulum stress (e.g., HSPC171 protein and HSC70), together with a downregulation of apoptosis related genes (e.g., programmed cell death 7) was observed. Apoptosis and autophagy have previously been shown to occur in response to treatments with nanomaterials (Popp and Segatori, 2015). These processes are of high importance to organisms.…”

“…Apoptosis is critically important for the survival of multicellular organisms by getting rid of damaged or infected cells that may interfere with normal function (Portt et al, 2011) whereas autophagy is an important multifunctional process, which cells use to recycle cellular constituents, a process that plays an important role in normal cellular homeostasis (Popp and Segatori, 2015). Under the present circumstances, it seems that these processes are activated to compensate the stress caused by the exposure to AuNP, in agreement with previous suggestions that autophagy is activated upon internalization of engineered nanomaterials as a protective response to what is perceived as foreign or toxic (Popp and Segatori, 2015). In the present study, it was shown that exposure to the lowest concentration of AuNP upregulated apoptosis-related genes and the highest AuNP concentration upregulated autophagy and downregulated apoptosis.…”

Influence of multi-walled carbon nanotubes on the cognitive abilities of Wistar rats

“…New materials are appearing in the world of modern technology, with nanomaterials, such as nanotubes, nanoballs, nanorods, quantum dots, immobilized nanoparticles and a number of other unusual structures, undergoing the most development and being particularly noteworthy (1). …”

“…As a result, their presence in people's everyday lives and the environmental burden they may cause is constantly increasing (1). …”