Study of phagocytic pathway in senescent cells.

ROBLEDO, ESTEBAN; COLOMBO M.I.; AGUILERA, MILTON

Congreso; SAIB-SAMIGE Joint meeting 2021 on line.; 2021

SAIB (Sociedad Argentina de Investigación en Bioquímica y Biología Molecular)

Senescence is defined as a state where proliferating cells lose their replicating capacity. This mechanism is triggered by different stimuli, such as oxidative stress, telomere shortening, DNA damage, mitochondrial damage and also is induced by oncogenes activity. Characteristics of senescent cells include irreversible growth arrest, increased cell size, expression of cyclin-dependent kinase inhibitor (CDKI), formation of senescence-associated heterochromatin foci and senescence-associated secretory phenotype (SASP). These changes attempt to prevent damaged cells from proliferating and causing expansive damage. It takes place in various tissues during different physiological and pathological processes such as tissue remodeling or injury, cancer, and aging. Phagocytosis is a process where pathogens are taken and eliminated by the cells. Furthermore, it is important for the elimination of apoptotic cells and, therefore, essential for tissue homeostasis. The mechanism of this process consists, once a particle is internalized, it is formed the primary phagosome. In order to eliminate the phagocytosed particle, the primary phagosome matures by decreasing pH and acquiring degradative capacity. Our study is focused on evaluating modifications endocytic and phagocytic pathways after senescence activation. Also, we are interested in the behavior of senescent cells against pathogens given the relevance of infectious processes in aging organisms. In order to reach senescence activation, due to oxidative stress, HeLa cells were treated with 250uM t-BHP for 2 hours. Afterwards, cells were analyzed by confocal microscopy and flow cytometry and we evaluated the composition and distribution of early and late endosomes pathway using specific markers, such as Rab-5, Rab-7 and LAMP-2. The senescence cells endocytic capacity was analyzed by dextran incorporation and phagocytosis, using formaldehyde-inactivated bacteria, by flow cytometry. The differences present in senescent cells help us understand the alterations in the response against pathogens in aging organisms.