Abstract
Purpose :
The molecular mechanisms that drive the development of the lens fibrotic disease, Posterior Capsule Opacification (PCO), in response to cataract surgery are not completely understood. Mitochondria serve as central coordinators of cell function through their ability to serve as a major source of energy, generate metabolites and reactive oxygen species (ROS), and through their impact on cell signaling. Whether mitochondria play a role in the development of PCO is not known. In this study, we explore the hypothesis that the development of lens fibrotic disease is associated with the remodeling of mitochondrial function.
Methods :
RNAseq analysis was performed on an ex vivo post-cataract surgery chick model, which recapitulates the major features of PCO, at Day 0 (D0) before fibrosis and D3 post-injury, a time when fibrotic markers are expressed. In addition, ex vivo surgery cultures were labeled live with a MitoSOX probe to determine ROS production by mitochondria (mtROS) post-cataract surgery wounding. The mitochondrial network was also examined, by labeling cultures for Tom20 to identify all mitochondria regardless of membrane potential, and using MitoTracker Red, to specifically label active mitochondria.
Results :
Our unbiased transcriptome findings showed that lens fibrosis is associated with gene reprogramming focused on remodeling mitochondrial function and metabolism. G0 analysis comparing D0 to D3 (fibrosis) post-cataract surgery injury, showed a decrease in major energy producing pathway, mitochondrial respiratory chain assembly and oxidative phosphorylation, supporting a downregulation of oxidative phosphorylation. Transcripts for rate-limiting enzymes of glutaminolysis (GLS), and also for glycolysis (PFKM and HK1), were upregulated, providing evidence that lens fibrosis involves metabolic rewiring. Acquisition to a lens fibrotic phenotype was associated with an increase in mtROS production specifically within leading edge cells that serve as myofibroblast progenitors linked to driving fibrosis. Mitochondria appeared to traffic along cytoskeletal elements within myofibroblast progenitor cells; consistent with these observations, we observed an increase in transcripts that upregulate mitochondrial fission (DNM1L, MFF, and MTFR1) and motility (RHOT2).
Conclusions :
Our findings support the hypothesis that mitochondrial form, and function, and cellular metabolism are remodeled during lens fibrotic disease.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.