Abstract
Purpose :
We previously reported that hyperactivation of the mechanistic target of rapamycin complex 1 (mTORC1) in the retinal pigment epithlium (RPE) leads to RPE dysfunction, followed by degeneration of the photoreceptor and choroid. The goal of the current project is to investigate the underlying mechanisms that link hyperactive mTORC1 signaling in the RPE and choroid arophy.
Methods :
RPE-specific, TSC1-deficient mice were established by crossing TSC1-floxed mice with transgenic mice with Bestrophin promoter-driven Cre expression. Choroid thinning was examined on both histological sections and cryosections. Flow cytometry analysis was used to characterize and compare cell populations of choroid between RPE-TSC1 deficient mice and littermates. The expression level of target genes were measured at both mRNA and protein levels using q-RT PCR and western blot, respectively. The subcellular and tissue distribtuions of the proteins were examined using immunostaining on both cryosections of the posterior eye and flat-mounted RPE/choroid or choroid tissue only. The level of secreted vascular growth factors was determined by ELISA. Visual functions were measured by electroretinogram (ERG).
Results :
RPE-specific TSC1 deficient mice had choroid thinning. There was a progressive loss of choroicapillary markers. When analyzed for major regulators of choroidal vessel growth and homeostasis, we found increased production of Angiopoietin-2 from RPE with TSC1-deficiency.
Conclusions :
Hyperactive mTORC1 in the RPE caused choroid atrophy via RPE-derived Angiopoietin-2. Expression of Angiopoietin-2 in the RPE indiciates the paracrine effects in addition to the canonical autocrine regulation of choroidal endothelial function.
This is a 2021 ARVO Annual Meeting abstract.