Abstract WP277: <i>MYCT1</i> depletion exacerbates the inflammatory response in the retina post-stroke in a middle cerebral artery occlusion model

Introduction: Visual impairment is a common complication post-stroke that goes overlooked due to the focus on cerebral consequences. Approximately 60% of stroke survivors acquire new visual impairments after stroke. Middle cerebral artery occlusion (MCAO), the most common type of ischemic stroke (50.8%), was found to cause retinal ischemia in mice due to corresponding blockage of the ophthalmic artery. MYC target 1 (MYCT1), a significantly understudied protein, has shown to play a role in vascular development and reperfusion. Therefore, MYCT1 may serve as a therapeutic target for recovery of the retina following ischemic damage. Objective: The aim in this study is to understand MYCT1’s role in regulating inflammation after ischemic damage to the retina. Hypothesis: Lack of endothelial MYCT1 in mice leads to an exacerbated inflammatory response in the retina post-MCAO, causing greater damage and dysfunctional repair to the retina. Methods: C57BL/6J (WT) and MYCT1 endothelial-specific knockout mice ( Cdh5 ; Myct1 f/f ) were subjected to MCAO for 60 minutes via a filament inserted into the internal carotid artery, followed by withdrawal. After 24 hours of reperfusion, the mice were euthanized, eyes were collected, retinas were dissected, and protein samples were extracted for Western blot and mass spectrometry-based proteomics analyses. Results: The top 15 pathways from Kyoto Encyclopedia of Genes and Genomes (KEGG), with the 229 proteins that changed significantly in WT vs Cdh5;Myct1 f/f mice, included pathways of neurodegeneration-multiple diseases, chemical carcinogenesis-reactive oxygen species, and glutathione metabolism. In addition, Cdh5;Myct1 f/f mice showed a greater inflammatory response with increased levels of IL-6, VCAM-1, GFAP, and MAPK/ERK signaling. Increased levels of GSTM5 and NQO1 indicate greater oxidative stress. Changes in electron transport chain subunits indicate mitochondrial dysfunction. Protein levels show increased T cell recruitment and a bias of Th17 cell differentiation over regulatory T cells. Decreased cytoskeletal proteins, including TUBB2B, indicate cytoskeleton instability and neurodegeneration. Conclusion: MYCT1 regulates the inflammatory response in the retina post-stroke. Endothelial MYCT1 deletion leads to protein changes that indicate exacerbated inflammation, oxidative stress, mitochondrial dysfunction, cytoskeleton instability, and T cell recruitment, potentially causing greater neurodegenerative damage to the retina.