Appropriate development of the retinal vasculature is essential for vision. Moreover, abnormal blood vessel growth in diseases such as diabetic retinopathy, age related macular degeneration and retinopathy of prematurity are common causes of blindness. The Retinal Determination (RD) cascade is an evolutionarily conserved signaling pathway best studied in the context of fly eye development and includes proteins of the Eyes Absent (EYA) and Sine oculis homeobox (SIX) families. We have recently demonstrated that Eyes Absent plays an essential role in vascular development. We now have evidence that the SIX family of transcription factors mechanistically synergize with EYA, and that the SIX proteins in both macrophages and in endothelial cells participate in regulating angiogenesis. This competing renewal application builds upon these observations to specifically test the role of the SIX proteins in developmental and pathological retinal angiogenesis. We hypothesize that SIX1 in retinal myeloid cells upregulates VEGFC expression and thus promotes tip-to-stalk conversion and anastomoses in the adjacent retinal vasculature. SIX1/2 in endothelial cells promotes branching and proliferation during tubulogenesis as well as upregulating VEGFC expression, thus reinforcing the tip-to-stalk conversion. To test this hypothesis in vitro and in vivo we propose the following Specific Aims: (I) To elucidate the role of macrophage SIX1 in regulating retinal angiogenesis, and (II) To elucidate the role of endothelial SIX1/2 in retinal angiogenesis.
Each aim will be accomplished by integrating diverse techniques including mechanistic biochemistry, cell culture based assays, chemical biology and animal models of eye development and disease. The tangible outcomes of this project will include (1) the delineation of mechanisms by which retinal angiogenesis is regulated, (2) the identification and molecular characterization of a pathway that could be targeted for therapeutic benefit in proliferative retinopathies, and (3) the validation of lead small molecule inhibitors tht could be further developed as targeted therapeutics.

Public Health Relevance

This project will directly examine the molecular mechanism(s) by which the retinal vasculature develops in health and in disease. Such an understanding is fundamental to the design of strategies for countering vision loss associated with an ageing population (diabetic retinopathy and the wet form of age related macular degeneration), as well as in premature infants (retinopathy of prematurity). The project employs a multi-disciplinary approach that incorporates biochemical analyses of protein function, atomic structures of proteins and protein complexes, assays to examine cellular function, small molecule inhibitors to probe cellular mechanism, and animal models of normal eye development as well as disease states.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY014648-12
Application #
9251280
Study Section
Diseases and Pathophysiology of the Visual System Study Section (DPVS)
Program Officer
Shen, Grace L
Project Start
2003-04-01
Project End
2018-03-31
Budget Start
2017-04-01
Budget End
2018-03-31
Support Year
12
Fiscal Year
2017
Total Cost
$315,900
Indirect Cost
$113,400
Name
Cincinnati Children's Hospital Medical Center
Department
Type
Independent Hospitals
DUNS #
071284913
City
Cincinnati
State
OH
Country
United States
Zip Code
45229
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Riffle, Stephen; Pandey, Ram Naresh; Albert, Morgan et al. (2017) Linking hypoxia, DNA damage and proliferation in multicellular tumor spheroids. BMC Cancer 17:338
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Wang, Yuhua; Tadjuidje, Emmanuel; Pandey, Ram Naresh et al. (2016) The Eyes Absent Proteins in Developmental and Pathological Angiogenesis. Am J Pathol 186:568-78
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