Title: Single retinal ganglion cell transcriptomics in models of hereditary optic neuropathy
Funder: The Academy of Medical Sciences

Abstract: The intrinsically photosensitive retinal ganglion cells (ipRGCs) survive preferentially compared to other retinal ganglion cells (RGCs) in Leber’s Hereditary Optic Neuropathy (LHON) and Dominant Optic Atrophy (DOA). Therefore, the objective of this study is to determine What is different about the transcriptomic profile of these cells that allows them to survive compared with other RGC subtypes in inherited optic neuropathies? Our a priori hypothesis is that differentially expressed genes in these ipRGCs contribute to their selective neuroprotection against mitochondrial dysfunction. The overall aim of this work will be to identify such candidate neuroprotective genes in order that they may be exploited in future work, specifically in the development of mutation independent AAV gene and pharmacological therapies. Such therapies will be applicable not only to hereditary mitochondrial optic neuropathies such as these, but potentially more generally to other neuropathies (glaucoma) and degenerative neurological diseases where mitochondrial dysfunction is implicated (such as Parkinson’s and Alzheimer’s disease). Practically, RGCs will be isolated by thy1 immunopanning digested retinas from mouse models of LHON and DOA obtained from our collaborators, as well as controls. The Chromium 10X & Illumina platforms will be used to obtain single cell transcriptomic profiles of isolated cells. Subsequently, a comparison of transcriptomes in ipRGCs (cells expressing the melanopsin gene Opn4) to other RGCs will provide a list of candidate genes. These will be validated anatomically by immunohistochemistry of mouse model retina and functionally by knock down & over expression in RGC cell lines derived from patient fibroblasts.

Lay abstract: Leber’s hereditary optic neuropathy (LHON) and dominant optic atrophy (DOA) are two diseases where vision is lost as nerve cells in the eye die. In these diseases, nerve cells die due to problems with their mitochondria. Mitochondria are the cell’s ‘power-stations’ converting food (sugar) into energy that can be used by the cell. A particular rare type of nerve cell within the eye (the ‘ipRGC’) is much more resistant to mitochondrial problems than other cells. These ipRGCs survive late in both LHON and DOA, when most other nerve cells have died. We predict that that there are a number of genes, active in ipRGCs, that protect them from damage. Therefore, in this study, we will isolate ipRGCs from the eyes of mice suffering from LHON and DOA. We will use a state-of-the-art genetic technique to determine which genes are active in each of these cells. This will then be compared to the genes we find to be active in eye nerve cells more generally. This will provide a list of genes potentially responsible for ipRGC resistance to death in LHON and DOA. These genes will then be manipulated in nerve cells growing in the lab, originally donated by patients with LHON and DOA. This will be essential to developing a new therapy to protect all nerve cells in the eye. Excitingly, such a treatment holds huge promise as poor mitochondria function is known to be important in many more common diseases (such as glaucoma, Alzheimer’s and Parkinson’s diseases).

Research activity codes: 1.1 NORMAL BIOLOGICAL DEVELOPMENT AND FUNCTIONING;2.1 BIOLOGICAL AND ENDOGENOUS FACTORS
Health categories: EYE;NEUROLOGICAL