Phagosome maturation during endosome interaction revealed by partial rhodopsin processing in retinal pigment epithelium.
J Cell Sci
; 127(Pt 17): 3852-61, 2014 Sep 01.
Article
em En
| MEDLINE
| ID: mdl-25074813
ABSTRACT
Defects in phagocytosis and degradation of photoreceptor outer segments (POS) by the retinal pigment epithelium (RPE) are associated with aging and retinal disease. The daily burst of rod outer segment (ROS) phagocytosis by the RPE provides a unique opportunity to analyse phagosome processing in vivo. In mouse retinae, phagosomes containing stacked rhodopsin-rich discs were identified by immuno-electron microscopy. Early apical phagosomes stained with antibodies against both cytoplasmic and intradiscal domains of rhodopsin. During phagosome maturation, a remarkably synchronised loss of the cytoplasmic epitope coincided with movement to the cell body and preceded phagosome-lysosome fusion and disc degradation. Loss of the intradiscal rhodopsin epitope and disc digestion occurred upon fusion with cathepsin-D-positive lysosomes. The same sequential stages of phagosome maturation were identified in cultured RPE and macrophages challenged with isolated POS. Loss of the cytoplasmic rhodopsin epitope was insensitive to pH but sensitive to protease inhibition and coincided with the interaction of phagosomes with endosomes. Thus, during pre-lysosomal maturation of ROS-containing phagosomes, limited rhodopsin processing occurs upon interaction with endosomes. This potentially provides a sensitive readout of phagosome-endosome interactions that is applicable to multiple phagocytes.
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MEDLINE
Assunto principal:
Fagocitose
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Endossomos
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Rodopsina
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Fagossomos
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Epitélio Pigmentado da Retina
Limite:
Animals
Idioma:
En
Ano de publicação:
2014
Tipo de documento:
Article