Leber congenital amaurosis 8 (LCA8) is the most severe, non-treatable, early-onset (usually at birth) blinding disease that is caused by recessive mutations in Crumbs homolog 1 (Crb1) gene. About 20% of children attending schools for the blind around world are affected by LCA. Development of effective, mechanism-based therapies require models that replicate human LCA8 pathology. Current mouse models have limitations in reproducing human phenotypes partly due to partial gene ablation in ocular tissues, thus pathogenic mechanism studies at the cellular and molecular levels are inadequate. The newly-generated, improved mouse model using conditional ablation of Crb1 and its paralog, Crb2, exhibits main features of LCA8 including thick retina, indistinct retinal lamination, defects in the retinal pigment epithelium, and most importantly, the early- onset visual loss at the eye opening stage. Intriguingly, our data also indicate that retinal pathology starts in the retinal progenitor cells (RPCs), unlike most other types of LCA. Mutant RPCs undergo defective interkinetic nuclear migration that may alter cellular processes involved in cell proliferation, growth, apico-basal polarity, and actomyosin cytoskeleton regulation. Additionally, we found that several signaling cascades were severely altered; decreased Yap signaling essential for the proliferation of the RPCs and cell survival; increased mTOR pathway implicated in cell growth and proliferation; over-activated RhoA-ROCK signaling regulating cytoskeleton dynamics by controlling actomyosin assembly. Therefore, we hypothesize that perturbed Crb1/Crb2 downstream signaling activities play crucial roles in the initial pathogenesis of LCA8 in the RPCs. To test this, we will first fully assess the development of LCA8 pathology using histological, immunofluorescence assays along with a non-invasive, longitudinal imaging for quantifying retinal lesions. Second, we will delineate RPC-specific, cellular and molecular mechanisms underlying LCA8 pathogenesis. Third, we will define signaling pathway-dependent contributions to LCA8 pathology by genetic and pharmacological approaches.

Public Health Relevance

PROJECT NARATIVE Early-onset, degenerative retinal diseases disturb every steps of affected children. Disrupted retinal architecture underlies the early-onset, severe loss of vision in LCA8. Our main goal is to generate genuine mouse model that recapitulate the features of human patients. In addition, this project is focused on elucidating molecular and cellular basis of the disease-causing, detrimental signaling events.

National Institute of Health (NIH)
National Eye Institute (NEI)
Research Project (R01)
Project #
Application #
Study Section
Diseases and Pathophysiology of the Visual System Study Section (DPVS)
Program Officer
Shen, Grace L
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Temple University
Internal Medicine/Medicine
Schools of Medicine
United States
Zip Code
Kim, Jin Young; Park, Raehee; Lee, Jin Hwan J et al. (2016) Yap is essential for retinal progenitor cell cycle progression and RPE cell fate acquisition in the developing mouse eye. Dev Biol 419:336-347
Cho, Seo-Hee; Song, Ji Yun; Shin, Jinyeon et al. (2016) Neonatal disease environment limits the efficacy of retinal transplantation in the LCA8 mouse model. BMC Ophthalmol 16:193
Park, Jun Young; Hughes, Lucinda J; Moon, Uk Yeol et al. (2016) The apical complex protein Pals1 is required to maintain cerebellar progenitor cells in a proliferative state. Development 143:133-46
Kim, Jin Young; Song, Ji Yun; Karnam, Santi et al. (2015) Common and distinctive localization patterns of Crumbs polarity complex proteins in the mammalian eye. Gene Expr Patterns 17:31-7
Song, Ji Yun; Park, Raehee; Kim, Jin Young et al. (2014) Dual function of Yap in the regulation of lens progenitor cells and cellular polarity. Dev Biol 386:281-90
Cho, Seo-Hee; Kim, Jin Young; Simons, David L et al. (2012) Genetic ablation of Pals1 in retinal progenitor cells models the retinal pathology of Leber congenital amaurosis. Hum Mol Genet 21:2663-76