Showing papers by "Paloma B. Liton published in 2013"
TL;DR: It is proposed that diminished autophagic flux induced by oxidative stress might represent one of the factors leading to progressive failure of cellular TM function with age and contribute to the pathogenesis of primary open angle glaucoma.
Abstract: Increasing evidence suggests oxidative damage as a key factor contributing to the failure of the conventional outflow pathway tissue to maintain appropriate levels of intraocular pressure, and thus increase the risk for developing glaucoma, a late-onset disease which is the second leading cause of permanent blindness worldwide. Autophagy is emerging as an essential cellular survival mechanism against a variety of stressors, including oxidative stress. Here, we have monitored, by using different methodologies (LC3-I to LC3-II turnover, tfLC3, and Cyto ID), the induction of autophagy and autophagy flux in TM cells subjected to a normobaric hyperoxic model of mild chronic oxidative stress. Our data indicate the MTOR-mediated activation of autophagy and nuclear translocation of TFEB in oxidatively stressed TM cells, as well as the role of autophagy in the occurrence of SA-GLB1/SA-β-gal. Concomitant with the activation of the autophagic pathway, TM cells grown under oxidative stress conditions displayed, however, reduced cathepsin (CTS) activities, reduced lysosomal acidification and impaired CTSB proteolytic maturation, resulting in decreased autophagic flux. We propose that diminished autophagic flux induced by oxidative stress might represent one of the factors leading to progressive failure of cellular TM function with age and contribute to the pathogenesis of primary open angle glaucoma.
94 citations
TL;DR: A potential role of phagocytosis in outflow pathway tissue homeostasis through the up-regulation and/or proteolytic activation of extracellular matrix remodeling genes is suggested.
Abstract: Cells in the trabecular meshwork (TM), a tissue responsible for draining aqueous humor out of the eye, are known to be highly phagocytic. Phagocytic activity in TM cells is thought to play an important role in outflow pathway physiology. However, the molecular mechanisms triggered by phagocytosis in TM cells are unknown. Here we investigated the effects of chronic phagocytic stress on lysosomal function using different phagocytic ligands (E. coli, carboxylated beads, collagen I-coated beads, and pigment). Lysotracker red co-localization and electron micrographs showed the maturation of E. coli- and collagen I-coated beads-containing phagosomes into phagolysosomes. Maturation of phagosomes into phagolysosomes was not observed with carboxylated beads or pigment particles. In addition, phagocytosis of E. coli and collagen I-coated beads led to increased lysosomal mass, and the specific up-regulation and activity of cathepsin B (CTSB). Higher levels of membrane-bound and secreted CTSB were also detected. Moreover, in vivo zymography showed the intralysosomal degradation of ECM components associated with active CTSB, as well as an overall increased gelatinolytic activity in phagocytically challenged TM cells. This increased gelatinolytic activity with phagocytosis was partially blocked with an intracellular CTSB inhibitor. Altogether, these results suggest a potential role of phagocytosis in outflow pathway tissue homeostasis through the up-regulation and/or proteolytic activation of extracellular matrix remodeling genes.
38 citations
TL;DR: The αvβ5 integrin-FAK-mediated pathway regulates phagocytosis in TM cells and this pathway is inhibited by activation of αv β3 integrins, which suggests that changes in integrin expression and activity may be responsible for alterations in phagocytes observed in steroid induced glaucoma.
Abstract: Purpose.
To investigate the roles of αvβ3 and αvβ5 integrins in phagocytosis in human trabecular meshwork (HTM) cells.
37 citations