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About the Authors:
Pawat Seritrakul
Roles Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Software, Validation, Visualization, Writing - original draft, Writing - review & editing
Affiliations Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX, United States of America, Departments of Ophthalmology, and Developmental Biology, The Louis J. Fox Center for Vision Restoration, The McGowan Institute for Regenerative Medicine, The University of Pittsburgh School of Medicine, Pittsburgh, PA, United States of America
ORCID http://orcid.org/0000-0002-8320-6789
Jeffrey M. Gross
Roles Conceptualization, Formal analysis, Funding acquisition, Project administration, Resources, Supervision, Writing - review & editing
* E-mail: [email protected]
Affiliations Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX, United States of America, Departments of Ophthalmology, and Developmental Biology, The Louis J. Fox Center for Vision Restoration, The McGowan Institute for Regenerative Medicine, The University of Pittsburgh School of Medicine, Pittsburgh, PA, United States of America
ORCID http://orcid.org/0000-0002-9422-6312Abstract
DNA hydroxymethylation has recently been shown to play critical roles in regulating gene expression and terminal differentiation events in a variety of developmental contexts. However, little is known about its function during eye development. Methylcytosine dioxygenases of the Tet family convert 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC), an epigenetic mark thought to serve as a precursor for DNA demethylation and as a stable mark in neurons. Here, we report a requirement for Tet activity during zebrafish retinal neurogenesis. In tet2-/-;tet3-/- mutants, retinal neurons are specified but most fail to terminally differentiate. While differentiation of the first born retinal neurons, the retinal ganglion cells (RGCs), is less affected in tet2-/-;tet3-/- mutants than other retinal cell types, the majority of RGCs do not undergo terminal morphogenesis and form axons. Moreover, the few photoreceptors that differentiate in tet2-/-;tet3-/- mutants fail to form outer segments, suggesting that Tet function is also required for terminal morphogenesis of differentiated retinal neurons. Mosaic analyses revealed a surprising cell non-autonomous requirement for tet2 and tet3 activity in facilitating retinal neurogenesis. Through a combination of candidate gene analysis, transcriptomics and pharmacological manipulations, we identified the Notch and Wnt pathways as cell-extrinsic pathways regulated by tet2 and tet3 activity during RGC differentiation and morphogenesis. Transcriptome analyses also revealed the ectopic expression of...