Project Summary:
Retinal degenerative diseases are a major medical issue for society. One potentially exciting approach to
restore vision is the regeneration of lost retinal neurons from an endogenous population of retinal cells, the
Müller glia. We are studying this process in zebrafish, which unlike mammals, exhibits a natural Müller glia-
dependent retinal regeneration response. However, there are two major gaps in our understanding of this
retinal regeneration response. The first is why rapid acute damage exhibits a regeneration response and a
slow chronic damage, which is what is often observed in human retinal degenerative diseases, does not induce
a regeneration response in zebrafish. The second gap in our understanding is the role of the microglia, the
immune cells of the central nervous system, which are the major source of inflammation resulting from damage
and a known regulator of the Müller glia-dependent retinal regeneration. We will address these two gaps in
three Specific Aims. Aim 1 will determine the potential of two different chronic zebrafish retinal degeneration
mutants (gosh, an early onset rapid cone photoreceptor degeneration mutant and cep290, a late onset slow
cone degeneration mutant) to induce Müller glia proliferation and regenerate lost cones using different stimuli.
We will determine to what extent either a secondary acute damage or the introduction of molecules that
stimulate Müller glia proliferation can induce cone regeneration in chronically damaged fish and how complete
the regeneration process is. In Aim 2, we will conduct a comprehensive and unbiased, comparative analysis of
gene expression and chromatin accessibility in Müller glia and microglia using a multiomic single-nuclear RNA-
Seq and ATAC-Seq analysis in these two chronic degeneration mutants, along with two mouse chronic retinal
degeneration mutants. We will determine the similarities and differences in gene expression and chromatin
accessibility in the Müller glia and microglia between the acutely and chronically damaged retinas. These
bioinformatic analyses will reveal transcription factors and signaling (cytokine, growth factors, ligand/ receptor
pairs) molecules that are essential for regeneration following acute damage and blocking regeneration in the
chronically damaged zebrafish retina. We will also determine the differences and similarities between the
chronically damaged zebrafish and mouse retinas to determine how similar these regulatory components are
between the zebrafish and mouse. Aim 3 will then functionally test the roles of the candidate regulators
previously identified in our scRNA-Seq datasets or in Aim 2 by either modifying their expression or their activity
in the chronically and acutely damaged zebrafish retina. This work will be the first molecular analysis of how
retinal regeneration is regulated in the chronically damaged zebrafish retina and will be critical in the translation
of Müller glial-dependent retinal regenerative therapies into human retinal degenerative diseases.
