Phagosome maturation during endosome interaction revealed by partial rhodopsin processing in retinal pigment epithelium.
Bottom Line: 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.
Affiliation: Molecular Medicine Section, National Heart and Lung Institute, Imperial College London, London SW7 2AZ, UK UCL Institute of Ophthalmology, University College London, London EC1V 9EL, UK.Show MeSH
Related in: MedlinePlus
Mentions: To determine whether the loss of the cytoplasmic rhodopsin epitope correlated with phagosome movement from the apical to the basal region of the cell, the position of phagosomes in the RPE in relation to their labelling for both rhodopsin antibodies was analysed. As shown in Fig. 2A, >90% of early phagosomes (1D4 positive, RET-P1 positive) were apical (at or above the tight junctions), whereas late phagosomes (1D4 negative, RET-P1 positive) could be both apical and basal (below the tight junctions), although most (>75%) were basal. This suggests that the loss of the cytoplasmic epitope of rhodopsin occurs early in the maturation process and might precede movement to the basal region.
Affiliation: Molecular Medicine Section, National Heart and Lung Institute, Imperial College London, London SW7 2AZ, UK UCL Institute of Ophthalmology, University College London, London EC1V 9EL, UK.