Abstract
Retinal ganglion cells (RGCs) are the only projection neurons in the retina that relay visual information to the
brain. These neurons, which collectively form the optic nerve, are highly vulnerable when their axons are
damaged. Preclinical animal studies have tested several approaches to promote RGC survival following axonal
damage. Clinical trials aimed at assessing the neuroprotective effects are currently underway. However, attaining
strong neuroprotection for patients suffering from optic neuropathy remains an elusive goal.
Long noncoding RNAs (LncRNAs) are a diverse class of transcribed RNAs, defined as transcripts with lengths
exceeding 200 nucleotides that do not encode proteins. Although several lncRNAs have been shown to play
vital roles in regulating gene expression networks in the central nervous system (CNS), the functional roles of
the majority of lncRNAs are unknown. In our recent effort to investigate RGC type-specific gene expression, we
performed RNAsequencing (RNA-seq) on distinct RGC populations. Through this work, we identified hundreds
of lncRNAs that are uniquely induced in different RGC types after axonal injury. The functions of these lncRNAs
remain to be determined.
To investigate lncRNAs’ functional roles, and to examine whether modulating the expression of injury-induced
lncRNAs affects RGC survival after axonal injury, we generated adeno-associated viruses (AAV) expressing
shRNAs against select lncRNAs, and carried out an in vivo screen using optic nerve crush (ONC). Through this
work, we find that silencing one lncRNA results in striking neuroprotection for RGCs after ONC. This lncRNA is
a long intergenic non-coding RNA (lincRNA) which we name optic nerve injury-induced lncRNA 1 or Onil1. Like
the vast majority of lncRNAs that we found to be differentially expressed in RGCs, virtually nothing is known
about this lincRNA. Overall, our study provides us with an exciting and unique opportunity to investigate the role
of lncRNAs in regulating RGC survival after injury, and elucidate the possible molecular mechanisms underlying
this process. In this proposal, we seek to combine in vivo models of optic nerve injury, functional and behavioral
assays, and bioinformatics to investigate the contribution of Onil1 and other lncRNAs in regulating RGC survival.
To this end, in Aim 1, we will systemically assess the extent of RGC protection conferred by silencing lncRNAs
in adult RGCs after ONC. In Aim 2, we will assess whether silencing lncRNA induces RGC protection and
functional rescue in mouse models of glaucoma. Lastly, in Aim 3, we will use immunostaining, RNA-seq, ATAC-
seq and ChIRP-MS to investigate the mechanisms by which Onil1 regulates RGC survival.