Abstract
Purpose :
Cellular senescence contributes to age-related tissue degeneration. Mitochondrial dysfunction is associated with senescence, but how mitochondria regulate cellular senescence is not well established. Mitochondrial serine/threonine protein phosphatase 5 (PGAM5), a mitochondrial membrane protein, has been shown to regulate mitophagy, Keap1- Nrf2 and TNF signaling pathways. Its function in RPE cells is still unknown. The purpose of the project is to test the function of PGAM5 in mitochondrial homeostasis and RPE senescence.
Methods :
Stable PGAM5 -/- ARPE-19 cell lines were established using CRISPR-Cas9 system. The mitochondrial and cellular phenotypes of the cells were examined. Cellular reactive oxygen species (ROS) and ATP levels were measured using standard methods. Immunostaining and Western blot analysis were employed to detect the signaling pathways and the molecular markers for senescence regulated by PGAM5. The sensitivity of the cells to oxidative stress NaIO3 was also tested. PGAM5 overexpression was used in the rescue experiments.
Results :
We found mitochondrial fission and mitophagy were repressed in PGAM5 -/- ARPE-19 cells under normal and stress conditions, as shown by the maintained mitochondrial network in the cells. This phenotype is accompanied by upregulation of ATP and ROS levels in the cells. As results, AMPK activity is repressed, which activates mTOR signaling .In return, cellular senescence and oxidative stress response were altered in PGAM5-/- RPE cells.
Conclusions :
Our results establish a close relationship among mitochondrial homeostasis, senescence and oxidative response in RPE cells. PGAM5 regulates mitochondrial homeostasis, and through which regulates RPE cellular senescence via AMPK-mTOR pathway.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.