The research and the understanding of the new mechanisms involved in the mitochondrial quality control can allow to identify new therapeutic treatments of neurodegenerative diseases involving mitochondrial dysfunction. In this context the analysis of Delayed Luminescence emitted by in vitro models for the study of Alzheimer's disease (AD) can give new insight of the alterations of mitochondria functional state and of the collective properties linked to the electronic transport in the mitochondrial respiratory chain. It well known that that AD is characterized by intracellular and extracellular protein aggregates in the brain, including microtubule-associated protein tau and cleavage products of the amyloid precursor protein, beta-amyloid (A?). Several evidences have shown that elevated A? levels contribute to the mitochondrial abnormalities. Amyloid precursor protein (APP) and A? are found in mitochondrial membranes and interact with mitochondrial proteins. Overproduction of the APP and A? may affect dynamics of mitochondrial fusion/fission, impair mitochondrial transport, disrupt the electron transfer chain, increase reactive oxygen species (ROS) production, and alteration of calcium homeostasis, which are the hallmarks of mitochondrial diseases. Further, a significant reduction of the protein content of Complex I of the respiratory chain, of its activity and of energy production, characteristic signs of the reduction of energy metabolism associated to AD, were observed. Delayed Luminescence (DL) is the phenomenon of photo-induced and ultra-weak emission of optical photons. Its temporal decay dynamics extends over time (seconds or minutes) after switching off the excitation source. The intensity is about 103-105 times lower than that of fluorescence or phosphorescence. Previous researches carried on Jurkat-T leukemic cells, follicular tumors and glioblastoma, also using substances that target the mitochondria, and in particular the process of electron transfer in Complex I, have shown how the DL is able to detect the activation of apoptotic pathways and oxidative stress. The investigation was performed on an in vitro animal model for the study of AD by using primary cell cultures of Olfactory Ensheathing Cells (OECs), glial cells of the olfactory system and whose loss of functionality is the first marker of the AD. The cell cultures have been exposed to A?(1-42) native full-length peptide or to A?(25-35), a toxic fragment of A?, or A?(35-25), a no toxic A? fragment both in absence and in presence of Astaxanthin, a well-known antioxidant. The DL experiments were performed, using a dedicated equipment, on 20µl single drops of cell culture suspension. DL intensity and kinetics changes as a function of the treatments were measured. In particular, an increase in DL emission, when compared with the untreated cells used as control, was observed when the cells were exposed to A?(25-35) fragment. This emission appears quenched in presence of Astaxanthin.
Delayed Luminescence by an in vitro model for the study of mechanism involved in Alzheimer's disease
Rosalia Pellitteri;
2019
Abstract
The research and the understanding of the new mechanisms involved in the mitochondrial quality control can allow to identify new therapeutic treatments of neurodegenerative diseases involving mitochondrial dysfunction. In this context the analysis of Delayed Luminescence emitted by in vitro models for the study of Alzheimer's disease (AD) can give new insight of the alterations of mitochondria functional state and of the collective properties linked to the electronic transport in the mitochondrial respiratory chain. It well known that that AD is characterized by intracellular and extracellular protein aggregates in the brain, including microtubule-associated protein tau and cleavage products of the amyloid precursor protein, beta-amyloid (A?). Several evidences have shown that elevated A? levels contribute to the mitochondrial abnormalities. Amyloid precursor protein (APP) and A? are found in mitochondrial membranes and interact with mitochondrial proteins. Overproduction of the APP and A? may affect dynamics of mitochondrial fusion/fission, impair mitochondrial transport, disrupt the electron transfer chain, increase reactive oxygen species (ROS) production, and alteration of calcium homeostasis, which are the hallmarks of mitochondrial diseases. Further, a significant reduction of the protein content of Complex I of the respiratory chain, of its activity and of energy production, characteristic signs of the reduction of energy metabolism associated to AD, were observed. Delayed Luminescence (DL) is the phenomenon of photo-induced and ultra-weak emission of optical photons. Its temporal decay dynamics extends over time (seconds or minutes) after switching off the excitation source. The intensity is about 103-105 times lower than that of fluorescence or phosphorescence. Previous researches carried on Jurkat-T leukemic cells, follicular tumors and glioblastoma, also using substances that target the mitochondria, and in particular the process of electron transfer in Complex I, have shown how the DL is able to detect the activation of apoptotic pathways and oxidative stress. The investigation was performed on an in vitro animal model for the study of AD by using primary cell cultures of Olfactory Ensheathing Cells (OECs), glial cells of the olfactory system and whose loss of functionality is the first marker of the AD. The cell cultures have been exposed to A?(1-42) native full-length peptide or to A?(25-35), a toxic fragment of A?, or A?(35-25), a no toxic A? fragment both in absence and in presence of Astaxanthin, a well-known antioxidant. The DL experiments were performed, using a dedicated equipment, on 20µl single drops of cell culture suspension. DL intensity and kinetics changes as a function of the treatments were measured. In particular, an increase in DL emission, when compared with the untreated cells used as control, was observed when the cells were exposed to A?(25-35) fragment. This emission appears quenched in presence of Astaxanthin.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
