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Mitophagy in the Retinal Pigment Epithelium of Dry Age-Related Macular Degeneration Investigated in the <i>NFE2L2</i>/<i>PGC-1α</i><sup>-/-</sup> Mouse Model
oleh: Iswariyaraja Sridevi Gurubaran, Johanna Viiri, Ali Koskela, Juha M.T. Hyttinen, Jussi J. Paterno, Gréta Kis, Miklós Antal, Arto Urtti, Anu Kauppinen, Szabolcs Felszeghy, Kai Kaarniranta
Format: | Article |
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Diterbitkan: | MDPI AG 2020-03-01 |
Deskripsi
Increased oxidative stress and mitochondrial damage are observed in protein aggregation diseases, such as age-related macular degeneration (AMD). We have recently reported elevated levels of oxidative stress markers, damaged mitochondria, accumulating lysosomal lipofuscin and extracellular drusen-like structures in the retinal pigment epithelial cells (RPE) of the dry AMD-resembling <i>NFE2L2</i>/<i>PGC1α</i> double knockout (dKO) mouse model. Here, we provide evidence of a disturbance in the autolysosomal machinery handling mitochondrial clearance in the RPE cells of one-year-old <i>NFE2L2</i>/<i>PGC1α</i>-deficient mice. Confocal immunohistochemical analysis revealed an upregulation of autophagosome marker microtubule-associated proteins 1A/1B light chain 3B (LC3B) as well as numerous mitophagy markers, such as PTE-induced putative kinase 1 (PINK1) and E3 ubiquitin ligase (PARKIN) together with damaged mitochondria. However, we detected no evidence of increased autolysosome formation in transmission electron micrographs or of colocalization of lysosomal marker LAMP2 (lysosome-associated membrane protein 2) and the mitochondrial marker ATP synthase β in confocal micrographs. Interestingly, we observed an upregulation of late autolysosomal fusion Ras-related protein (Rab7) in the perinuclear space of RPE cells together with autofluorescence aggregates. Our results reveal that there is at least a relative decrease of mitophagy in the RPE cells of <i>NFE2L2</i>/<i>PGC1α</i> dKO mice. This further supports the hypothesis that mitophagy is a putative therapy target in AMD-like pathology.