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.

Public Health Relevance

. 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 that could be further developed as targeted therapeutics.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
2R01EY014648-09A1
Application #
8629028
Study Section
Special Emphasis Panel (DPVS)
Program Officer
Shen, Grace L
Project Start
2003-04-01
Project End
2018-03-31
Budget Start
2014-04-01
Budget End
2015-03-31
Support Year
9
Fiscal Year
2014
Total Cost
$351,000
Indirect Cost
$126,000
Name
Cincinnati Children's Hospital Medical Center
Department
Type
DUNS #
071284913
City
Cincinnati
State
OH
Country
United States
Zip Code
45229
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Tadjuidje, Emmanuel; Hegde, Rashmi S (2013) The Eyes Absent proteins in development and disease. Cell Mol Life Sci 70:1897-913
Ponferrada, Virgilio G; Fan, Jieqing; Vallance, Jefferson E et al. (2012) CRIM1 complexes with ýý-catenin and cadherins, stabilizes cell-cell junctions and is critical for neural morphogenesis. PLoS One 7:e32635
Tadjuidje, Emmanuel; Wang, Tim Sen; Pandey, Ram Naresh et al. (2012) The EYA tyrosine phosphatase activity is pro-angiogenic and is inhibited by benzbromarone. PLoS One 7:e34806
Miller, S J; Lan, Z D; Hardiman, A et al. (2010) Inhibition of Eyes Absent Homolog 4 expression induces malignant peripheral nerve sheath tumor necrosis. Oncogene 29:368-79
Pandey, R N; Rani, R; Yeo, E-J et al. (2010) The Eyes Absent phosphatase-transactivator proteins promote proliferation, transformation, migration, and invasion of tumor cells. Oncogene 29:3715-22
Hu, Shengyong; Mamedova, Aygun; Hegde, Rashmi S (2008) DNA-binding and regulation mechanisms of the SIX family of retinal determination proteins. Biochemistry 47:3586-94
Liou, Benjamin; Kazimierczuk, Andrzej; Zhang, Min et al. (2006) Analyses of variant acid beta-glucosidases: effects of Gaucher disease mutations. J Biol Chem 281:4242-53
Rayapureddi, Jayanagendra P; Hegde, Rashmi S (2006) Branchio-oto-renal syndrome associated mutations in Eyes Absent 1 result in loss of phosphatase activity. FEBS Lett 580:3853-9
Seufert, Daniel W; Hegde, Rashmi S; Nekkalapudi, Srivamsi et al. (2005) Expression of a novel Ski-like gene in Xenopus development. Gene Expr Patterns 6:22-8

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