Cell proteins undergoes turnover by means of digestion and the resulting amino acids are used for synthesis of new proteins. However, the digestion of proteins in cells generates peptides which, in specific cases, have signaling function and may lead to changes in the profile of gene expression and gene silencing. The cell degestion of proteins can occur in the proteassomes that degradate ubiquitin-linked proteins and in the lisosomes. Lisosomes digest proteins that were endocytosed after fusion with endosome and also lisosomes digest proteins composing organelles that were target of autophagy including the mitophagy of aged mitochondria. In this scenario, it is expected that cytochrome c can be converted to a diversity of peptides including those containing the heme group that are named microperoxidases and endowed with well-known prooxidant potential. The present project has as the principal objective the investigation about a possible role of heme-containing tryptic fragments of cytochrome c, i.e., microperoxidases, in the modulation of genic expression of antioxidant enzymes. This investigation will be correlated with the capacity of these peptides to promote oxidative stress culminating with cell death. In the first step of the investigation it will be determined the most appropriate carriers for loading cells with microperoxidase and cytochrome c in such way that they will be targeted to lysosomes, where, it is expected the generation of cytochrome c-derivated peptides following mitochondria autophagy and protein digestion. The results will be compared with that obtained in conditions where the protein and peptides are loaded in cytosol, probably by electroporation. The protein and peptides deliver will be monitored by confocal microscopy to follow the carriers labeled with quantum dots in the presence of fluoresent dyes that are specific for lysosomes. In this step it will be also determined the cell death mechanisms resulting from the different deliver strategies. In the second step of the investigation, it will be studied the modulation of gene expression by the peptides delivered by the most appropriated technique for lysosomal location of delivered agents. The results will be compared with changes in gene expression promoted by autophagy inducers such as rapamicine and tamoxifen.
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