# Determining the role of CLN3 in the eye

> **NIH NIH R01** · UNIVERSITY OF ROCHESTER · 2021 · $490,935

## Abstract

ABSTRACT
Juvenile neuronal ceroid lipofuscinosis (JNCL), caused by mutations in the CLN3 gene, leads to
neurodegeneration and vision loss in early childhood. Vision loss in JNCL is due to retinal degeneration.
Specifically, in the retina, JNCL affects both the light sensing photoreceptor cells and their underlying
epithelium, RPE. Furthermore, photoreceptor cell loss in the JNCL retina has been linked to vision loss.
However, the molecular mechanism(s) underlying photoreceptor cell loss in JNCL are currently not known.
Preliminary studies in our laboratory utilizing human induced pluripotent stem cell (hiPSC)-derived retinal cells
suggest a novel role of CLN3 in maintaining key RPE structure (microvilli) and function (uptake of shed
photoreceptor outer segments or POS) that are essential for photoreceptor survival and therefore vision.
Specifically, JNCL hiPSC-RPE display microvilli disorganization/ballooning and impaired phagocytosis of POS
compared to control hiPSC-RPE cells. Notably, consistent with RPE microvilli dysfunction and reduced POS
uptake in JNCL hiPSC-RPE cells, RPE in the eyes of JNCL patients have reduced lipofuscin (breakdown
products of POS digestion). Together, these data suggest that “CLN3 is a RPE microvilli resident protein that
regulates POS uptake and CLN3 dysfunction in JNCL leads to impaired POS phagocytosis and subsequently
decreased lipofuscin accumulation in JNCL RPE cells.” To test this hypothesis, in this project, we propose to
employ ultrastructural and molecular studies on control and JNCL hiPSC-RPE cells. Specifically, we will first
utilize immunohistochemistry, RNAScope and subcellular fractionation techniques to confirm the localization of
a proportion of CLN3 in RPE cells to the apical microvilli in primary (mouse, porcine, human) and control hiPSC-
RPE. Next, we will compare i) microvilli structure and molecular composition and ii) POS binding and
internalization by control vs. JNCL hiPSC-RPE cells. Furthermore, to correlate the reduced POS phagocytosis
by JNCL hiPSC-RPE cells to reduced lipofuscin (autofluorescence accumulation) seen in JNCL RPE in vivo,
we will evaluate the pattern of autofluorescence accumulation (cell surface vs. intracellular) in parallel cultures
of control and JNCL hiPSC-RPE after chronic POS feeding (1-3 months). We will also validate our findings on
patient hiPSC-RPE cells using primary RPE/POS from a JNCL mouse and porcine model. Finally, we will utilize
in vivo retinal imaging of patients with JNCL in a longitudinal study to document the presence and amount of
autofluorescence/lipofuscin in the photoreceptor-RPE cell layer in relationship to photoreceptor vs. RPE cell
loss in patients progressing through the disease. Altogether, the knowledge gained from this study will provide
novel insights into i) the role of CLN3 in RPE physiology and ii) the plausible contribution of RPE dysfunction
to JNCL retinal pathophysiology.
!

## Key facts

- **NIH application ID:** 10114293
- **Project number:** 5R01EY030183-03
- **Recipient organization:** UNIVERSITY OF ROCHESTER
- **Principal Investigator:** Ruchira Singh
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $490,935
- **Award type:** 5
- **Project period:** 2019-04-01 → 2023-01-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10114293

## Citation

> US National Institutes of Health, RePORTER application 10114293, Determining the role of CLN3 in the eye (5R01EY030183-03). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10114293. Licensed CC0.

---

*[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*