title: Roles of αvβ5, FAK and MerTK in oxidative stress inhibition of RPE cell phagocytosis.
abstract: Efficient phagocytosis of photoreceptor outer segments (POS) by retinal pigment epithelial cells (RPE) plays a key role in biological renewal of these highly peroxidizable structures and in maintenance of retina health. Here, we used an in vitro RPE cell phagocytosis assay to investigate how sub-lethal oxidative stress modifies the key components of the cell phagocytic machinery leading to severe impairment of phagocytosis. Sub-lethal oxidative treatment, induced by hydrogen peroxide (H(2)O(2)), significantly inhibited binding and uptake of POS by RPE cells. However, sub-lethal oxidative stress did not affect cell surface expression of αvβ5 or RPE cell adhesion to αvβ5. Similarly, the enzymatic activity of mature cathepsin D was not altered upon challenge by oxidative stress. In contrast, studies of signaling molecules in the RPE cell phagocytic machinery revealed that sub-lethal oxidative stress inhibits POS-induced activation of FAK and MerTK. Our data demonstrate that sub-lethal oxidative treatment with H(2)O(2) inhibits phagocytic activity of ARPE-19 cells, in part by inhibiting FAK and MerTK.
authors.affiliation: Retinal Disease Research, Department of Biological Sciences, Allergan, Inc., RD3-2D, 2525 Dupont Drive, Irvine, CA 92612-1599, USA. qin_suofu@allergan.com
authors.forename: Suofu
authors.initials: S
authors.lastname: Qin
authors.forename: Gerard A
authors.initials: GA
authors.lastname: Rodrigues
mesh_terms: D002402:Cathepsin D / Q000378:metabolism; D002448:Cell Adhesion; D002460:Cell Line; D002470:Cell Survival; D005434:Flow Cytometry; D019084:Fluorescent Antibody Technique, Indirect; D051417:Focal Adhesion Kinase 1 / Q000502:physiology*; D006801:Humans; D006861:Hydrogen Peroxide / Q000633:toxicity; D015151:Immunoblotting; D018384:Oxidative Stress / Q000187:drug effects; D010587:Phagocytosis / Q000502:physiology*; D010766:Phosphorylation; D011518:Proto-Oncogene Proteins / Q000502:physiology*; D020794:Receptor Protein-Tyrosine Kinases / Q000502:physiology*; D019030:Receptors, Vitronectin / Q000502:physiology*; D055214:Retinal Photoreceptor Cell Outer Segment / Q000378:metabolism; D055213:Retinal Pigment Epithelium / Q000378:metabolism*; D000076202:c-Mer Tyrosine Kinase
chemical_list: D011518:Proto-Oncogene Proteins; D019030:Receptors, Vitronectin; C064660:integrin alphaVbeta5; D006861:Hydrogen Peroxide; C097072:MERTK protein, human; D020794:Receptor Protein-Tyrosine Kinases; D000076202:c-Mer Tyrosine Kinase; D051417:Focal Adhesion Kinase 1; C496050:PTK2 protein, human; C533922:CTSD protein, human; D002402:Cathepsin D