Abstract
Purpose :
In recent years, there has been a renewed interest in the role of angiotensin II (Ang II) in mediating the pathogenesis of glaucoma. Despite its (patho)physiological importance, the molecular mechanisms underlying Ang II-mediated oxidative stress remain largely unexplored. This study tested the hypothesis that the retina (R) is more susceptible to Ang II-elicited oxidative insult than the ophthalmic artery (OA) in an in vitro experimental mouse model.
Methods :
R and OA were isolated from male C57Bl/6J mice (n=15/group) and incubated overnight in medium containing either vehicle or Ang II (0.1 µM) at physiological conditions. Vascular proteins were extracted using our new in-house method specifically catered for robust protein extraction from microvascular samples and subjected to label-free quantitative mass spectrometry (MS)-based proteomics analysis. The acquired MS spectra were analysed by MaxQuant, followed by statistical analyses employing Perseus and, functional annotation and pathway analyses with Ingenuity Pathway Analysis.
Results :
Ang II elicited an acute differential expression of 312 and 34 proteins in the R and OA, respectively. Comparative protein expression analysis revealed that protein clusters involved in actin cytoskeleton and integrin-linked kinase signaling were significantly activated in the OA as part of the ocular vascular adaptation processes and, could be one measure to cope with oxidative stress. Conversely, a large majority of differentially expressed R proteins were involved in mitochondrial dysfunction (p=1.15E-24), inhibition of oxidative phosphorylation (p=2.00E-22) and, eukaryotic initiation factor 2 signalling, which is crucial for cell survival and is increasingly implicated in the pathogenesis of neurodegenerative diseases due to aberrant translational machinery in the cell.
Conclusions :
These findings corroborate with our hypothesis that the OA has inherent capacity to maintain cellular redox balance, whereas the R is highly susceptible to oxidative damage as evidenced by the inactivation of potential neuroprotective mechanisms. In gist, we provide the first in-depth insight into the key molecular and functional changes associated with acute adaptive response to oxidative stress in R compared to a retrobulbar vascular bed.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.