Retinal degeneration affects millions of people around the world each year. For the past decade, my lab has studied the coordination of proliferation and differentiation in the developing retina and in proliferative diseases of the retna such as retinoblastoma. Recently, we made a startling discovery that has fundamentally altered our understanding of the molecular and cellular mechanisms of retinal development and may also have a major impact on efforts to restore vision in some patients with retinal degeneration. We discovered that individual retinoblastoma tumor cells express multiple developmental programs simultaneously. This occurs through deregulation of the epigenetic programs that are directly or indirectly regulated by the RB1 protein. To explore this exciting finding further, we developed a novel experimental system to quantify the epigenetic reprogramming of individual retinal neurons by using 4 factors (Oct4, Klf4, Sox2, and Myc) and somatic cell nuclear transfer. We discovered that the epigenetic barriers to reprogramming dramatically differ across retinal cell types, and they are developmental stage-specific. Moreover, we have used the Sasai 3-dimensional culture system to show for the first time that mouse iPSCs can form the optic cup and differentiated retinae. One of the most exciting results from these experiments is that our iPSC lines derived from retinal neurons bypass the normal transition through anterior neuroectodermal specification. Instead, they retain retinal epigenetic memory and form exclusively retinal progenitor cells that differentiate into laminated retinae. The iPSCs derived from retinal neurons retain their epigenetic retinal memory for at least 50 passages, whereas iPSCs generated from genetically identical MEFs rarely produce retinae in this system. We have now shown that the photoreceptor precursors derived from retinal iPSCs can integrate into the retina;thus, iPSCs generated from mature retinal neurons may provide a renewable source of photoreceptor precursors for cell-replacement therapies to restore vision in those who suffer from retinal degeneration. This innovative research proposal will advance our understanding of the role of epigenetics in retinal development and begin to elucidate the molecular mechanisms and cell type-specific target genes involved in that process. It will also provide crucial preclinial data on the use of retinal-derived iPSCs for future clinical trials of photoreceptor-replacement therapy to treat retinal degeneration.

Public Health Relevance

We have developed a novel experimental system to epigenetically reprogram individual retinal neurons and quantify their ability to differentiate int retinae by using 3-dimensional retinal cultures. We discovered that induced pluripotent stem cells (iPSCs) from retinal neurons retain epigenetic memory of their retinal origins and produce photoreceptor precursors more efficiently than do iPSCs derived from other cell types. This discovery suggests that retinal iPSCs are an ideal renewable source of cells for photoreceptor precursor transplantation studies. Not only will this research advance the field of epigenetics in retinal development and contribute to efforts to restore photoreceptors lost during retinal degeneration, but also it will provide a large collection of mutant mice and cell lines to retina researchers.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY023619-02
Application #
8697055
Study Section
(BVS)
Program Officer
Neuhold, Lisa
Project Start
2013-08-01
Project End
2018-07-31
Budget Start
2014-08-01
Budget End
2015-07-31
Support Year
2
Fiscal Year
2014
Total Cost
Indirect Cost
Name
St. Jude Children's Research Hospital
Department
Type
DUNS #
City
Memphis
State
TN
Country
United States
Zip Code
38105
Wang, Lu; Hiler, Daniel; Xu, Beisi et al. (2018) Retinal Cell Type DNA Methylation and Histone Modifications Predict Reprogramming Efficiency and Retinogenesis in 3D Organoid Cultures. Cell Rep 22:2601-2614
Aldiri, Issam; Xu, Beisi; Wang, Lu et al. (2017) The Dynamic Epigenetic Landscape of the Retina During Development, Reprogramming, and Tumorigenesis. Neuron 94:550-568.e10
Hiler, Daniel J; Barabas, Marie E; Griffiths, Lyra M et al. (2016) Reprogramming of mouse retinal neurons and standardized quantification of their differentiation in 3D retinal cultures. Nat Protoc 11:1955-1976
Dyer, Michael A (2016) Biomedicine: An eye on retinal recovery. Nature 540:350-351
Chen, X; Pappo, A; Dyer, M A (2015) Pediatric solid tumor genomics and developmental pliancy. Oncogene 34:5207-15
Hiler, Daniel; Chen, Xiang; Hazen, Jennifer et al. (2015) Quantification of Retinogenesis in 3D Cultures Reveals Epigenetic Memory and Higher Efficiency in iPSCs Derived from Rod Photoreceptors. Cell Stem Cell 17:101-15
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McEvoy, Justina; Nagahawatte, Panduka; Finkelstein, David et al. (2014) RB1 gene inactivation by chromothripsis in human retinoblastoma. Oncotarget 5:438-50
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Chen, Xiang; Stewart, Elizabeth; Shelat, Anang A et al. (2013) Targeting oxidative stress in embryonal rhabdomyosarcoma. Cancer Cell 24:710-24

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