Intravitreal Endothelin-1 (ET-1) Injection Reduces Mitophagy in Retinal Ganglion Cells in MitoQC Mice

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dc.creatorBrooks, Calvin D.en_US
dc.creatorKodati, Binduen_US
dc.creatorInman, Deniseen_US
dc.creatorStankowska, Dorotaen_US
dc.creatorKrishnamoorthy, Raghuen_US
dc.creator.orcid0000-0002-3186-0404 (Brooks, Calvin D.)
dc.creator.orcid0000-0002-8522-4112 (Inman, Denise)
dc.date.accessioned2023-04-05T13:31:02Z
dc.date.available2023-04-05T13:31:02Z
dc.date.issued2023en_US
dc.description.abstractPurpose: The peptide endothelin-1 (ET-1), and its receptors are upregulated in the aqueous humor and retina in animal models of experimentally induced ocular hypertension, and have been shown to have a causative role in retinal ganglion cell (RGC) neurodegeneration. The purpose of this experiment was to assess the role of mitophagy in RGC neurodegeneration following intravitreal ET-1 administration in MitoQC mice. Methods: MitoQC mice (Gt(ROSA)26Sortm1(CAG-mCherry/GFP)Ganl on a C57BL/6 background) at the age of 3 months were used for the study. The mitochondria in these mice display both red and green fluorescence due to expression of a mCherry-GFP tag fused to the mitochondrial targeting sequence of an outer mitochondrial membrane protein, FIS1. When these mitochondria are trafficked to the lysosome for degradation, the green fluorescence is quenched, leaving only the red fluorescence. The MitoQC mice were intravitreally injected in both eyes with either ET-1 (1 nmole) or vehicle (water), and 72 hours following the injections the mice eyes were enucleated and retinal flat mounts were live-imaged using a Zeiss LSM 880 super resolution confocal microscope. Z-stack imaging was used to image the ganglion cell layer. For each Z layer, a threshold algorithm was used to define a region of interest (ROI) that included only areas with red fluorescence, after which red and green fluorescence were quantified for that ROI. Red/green fluorescence intensity was calculated and averaged per image. A red/green ratio larger than 1 is indicative of active mitophagy. This ratio was compared between ET-1 and vehicle-injected mice using a Mann-Whitney test (n=4 eyes per group). Results: At 72 hours after injection with ET-1, the average red/green fluorescence ratio in the RGCs was 0.86, while the vehicle-injected mice had an average red/green ratio of 1.29. These ratios were significantly different (P=0.0003), and the smaller red/green ratio in the ET-1 group indicates lesser mitophagy than the vehicle group. Conclusion: Mitophagy is known to be an important quality control mechanism for neuronal cell survival, and this study provides evidence that mitophagy is impaired by ET-1. The finding indicates that a decline in mitophagy may be associated with endothelin-mediated neurodegeneration in RGCs.en_US
dc.description.sponsorshipThis study is funded by the National Institutes of Health R01 EY028179 and T32 AG020494en_US
dc.identifier.urihttps://hdl.handle.net/20.500.12503/32158
dc.language.isoen
dc.titleIntravitreal Endothelin-1 (ET-1) Injection Reduces Mitophagy in Retinal Ganglion Cells in MitoQC Miceen_US
dc.typepresentationen_US
dc.type.materialtexten_US

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