Abstract
Purpose :
Dysfunction and degeneration of retinal pigment epithelium (RPE) cells leads to detrimental vision diseases such as dry age-related macular degeneration (AMD). One possibility for treating dry AMD is the stimulation of endogenous RPE regeneration, but little is known about the mechanisms that can drive RPE regeneration in vivo. The Hippo signaling pathway regulates cell proliferation and regeneration in many tissues, including during retina regeneration. In the developing RPE, the Hippo pathway is required for proliferation and cell fate decisions. Here, we manipulate the Hippo pathway by inactivating the upstream regulator Neurofibromin 2 (NF2) to investigate whether regeneration in the adult mouse RPE can be achieved after injury.
Methods :
We generated Nf2-conditional knockout (CKO) mice using the RPE-specific, doxycycline-inducible tet-on VMD2-Cre. We performed intraperitoneal or retro-orbital injections of sodium iodate (NaIO3) on 7- to 8-week-old mice to induce oxidative damage mainly to the RPE. Injury and potential regeneration were monitored over the course of 7-11 weeks post injury with electroretinography and optical coherence tomography. Proliferation and extent of regeneration were assessed by EdU incorporation and expression of OTX2 and RPE65 in the presumptive RPE layer 7.5 weeks post injury.
Results :
RPE injury reduced ERG Amax and Bmax responses by 80% of baseline at 10 days post-injury. Our preliminary results show that there can be improved tissue integrity and a trend for increased proliferation in adult Nf2-CKOs at 7.5 weeks post-injury. Furthermore, there are more OTX2-positive cells in the presumptive RPE, and several show colocalization with EdU (approx. 4-fold increase compared to damaged controls), suggesting potential de-novo production of RPE cells. We also detect nuclear localization of YAP in Nf2-CKO RPE.
Conclusions :
Our results indicate a potential role for Hippo pathway modulation in regenerative proliferation of mature, injured RPE. As mammalian adult RPE cells are post-mitotic, we hypothesize that NF2 normally inhibits regenerative proliferation of mature mammalian RPE through regulation of the Hippo/YAP-TAZ pathway. To investigate a potential mechanism, we are determining whether YAP and the transcription factor TEAD directly regulate RPE-specific gene expression to control RPE specification and maintenance.
This is a 2021 ARVO Annual Meeting abstract.