# Isolation of Congenital Stationary Night Blindness Genes

> **NIH NIH R01** · UNIVERSITY OF LOUISVILLE · 2021 · $527,373

## Abstract

Vision begins when light is converted to an electrical signal in the photoreceptors. Increases in light decrease
release of the neurotransmitter, glutamate, from cone and rod photoreceptor terminals, and decreases in light
increase its release. These changes in synaptic glutamate concentration are detected by two classes of bipolar
cells that then transmit the signal vertically through the retinal circuit to the ganglion cells. The neurotransmitter
changes also are detected by horizontal cells that provide lateral transmission in the form of feedback and
feedforward inhibition.
There are two classes of bipolar cells, hyperpolarizing (HBCs) and depolarizing (DBCs). HBCs utilize
ionotropic glutamate receptors and hyperpolarize in response to a light flash. DBCs utilize a metabotropic
glutamate receptor, mGluR6, that signals to TRPM1, depolarizing in response to a light flash. Defects in
transmission in DBCs results in complete congenital stationary night blindness (cCSNB). Mutations in GRM6,
NYX, TRPM1, GPR179 and LRIT3 cause cCSNB. The mechanism by which mGluR6 signals TRPM1 is largely
unknown. The long term goal of this project is study the molecular interactions between LRIT3 and known and
known components DBC signal transduction components. The specific aims are: 1) determine the function of
LRIT3 domains on rod and cone DBC mGluR6 signalplex assembly and signaling, and 2) Define protein
interactions required for DBC assembly and synaptic function, and 3) determine the function of LRFN1 and 2
on cone synapse function.
At the completion of this project, we will have characterized the function of LRIT3 and how it interacts with
currently unknown presynaptic partners. Further, we will have identified new candidate genes for congenital
stationary night blindness.

## Key facts

- **NIH application ID:** 10090463
- **Project number:** 5R01EY012354-20
- **Recipient organization:** UNIVERSITY OF LOUISVILLE
- **Principal Investigator:** RONALD G GREGG
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $527,373
- **Award type:** 5
- **Project period:** 1999-02-01 → 2023-01-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10090463

## Citation

> US National Institutes of Health, RePORTER application 10090463, Isolation of Congenital Stationary Night Blindness Genes (5R01EY012354-20). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10090463. Licensed CC0.

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