Our goal is to identify the regulatory networks that govern corneal development during embryogenesis and corneal healing post-natally, and to determine how disruption of these networks leads to sight-limiting defects in cornea function. As a key step towards this goal, our objective is to identify essential functions of PITX2 in corneal development and wound healing. Our central hypotheses are that activation of Cited2 and repression of Bmp2 and Bmp3 expression are essential mechanisms by which PITX2 regulates corneal development, and that reductions in Pitx2 gene dose adversely affect wound healing in the mature cornea. Our hypothesis was formulated on the basis of data showing that Cited2 expression is lost, and Bmp2 and Bmp3 expression is elevated in the developing cornea in the absence of PITX2, and that corneas of adult Pitx2+/- mice are cloudy and neovascularization is present following subtle insults. The significance of the proposed research is that knowledge of the genetic networks regulated by PITX2 in normal development and healing of the cornea will advance our understanding of these processes in general, an outcome that may in the future contribute to rationale design of improved therapies to prevent and treat vision loss due to corneal disease or injury. We will test our hypotheses via three specific aims: 1) Test the hypothesis that Cited2 is an essential downstream effector of Pitx2 during cornea development, 2) Test the hypothesis that PITX2- mediated suppression of Bmp2 and Bmp3 expression are additional essential mechanisms required for corneal development, and 3) Test the prediction that wound healing in the mature cornea is sensitive to Pitx2 gene dose.
Under aim 1, a conditional knockout strategy, which is already available in the applicant?s laboratory, will be used to specifically ablate Cited2 in ocular neural crest or surface ectoderm during corneal development, and assess corneal lineages and vascular growth using well-established approaches.
Under aim 2, a conditional strategy will be used to genetically activate Bmp2 or Bmp3 expression in ocular neural crest during corneal development using mice that we have generated, and the resulting mutants will be analyzed by the same criteria as in Aim 1.
Under aim 3, the defective Pitx2- allele that the applicant developed will be used to determine the effect(s) of Pitx2 gene dose on wound healing and neovascularization in the mature cornea. The expected outcome is that essential functions of PITX2 in the developing and mature cornea will be identified. The proposed research is innovative because essential functions of PITX2 in the developing and mature cornea will be determined, including the first demonstration that Cited2 expression and BMP signaling activity suppression are essential requirements for corneal development and wound healing. Ultimately, such knowledge may provide insights into productive new therapies for the prevention and treatment of vision loss due to corneal infection and injury. More broadly, the results may also have applicability to understanding mechanisms of neovascularization in certain cancers.

Public Health Relevance

Congenital or acquired defects that affect corneal transparency and refraction cause vision loss and blindness. The World Health Organization lists corneal blindness due to scarring and neovascularization as the fourth leading cause of vision loss worldwide. The overall goal of this proposal is to increase knowledge of the genetic pathways required for development and healing of the cornea.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY014126-17
Application #
9928980
Study Section
Special Emphasis Panel (ZRG1)
Program Officer
Mckie, George Ann
Project Start
2002-09-01
Project End
2021-05-31
Budget Start
2020-06-01
Budget End
2021-05-31
Support Year
17
Fiscal Year
2020
Total Cost
Indirect Cost
Name
University of Michigan Ann Arbor
Department
Ophthalmology
Type
Schools of Medicine
DUNS #
073133571
City
Ann Arbor
State
MI
Country
United States
Zip Code
48109
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Benson, Matthew D; Khor, Chiea C; Gage, Philip J et al. (2017) A targeted approach to genome-wide studies reveals new genetic associations with central corneal thickness. Mol Vis 23:952-962
Chen, Lisheng; Martino, Vanessa; Dombkowski, Alan et al. (2016) AP-2? Is a Downstream Effector of PITX2 Required to Specify Endothelium and Establish Angiogenic Privilege During Corneal Development. Invest Ophthalmol Vis Sci 57:1072-81
Chen, Lisheng; Gage, Philip J (2016) Heterozygous Pitx2 Null Mice Accurately Recapitulate the Ocular Features of Axenfeld-Rieger Syndrome and Congenital Glaucoma. Invest Ophthalmol Vis Sci 57:5023-5030
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Gage, Philip J; Hurd, Elizabeth A; Martin, Donna M (2015) Mouse Models for the Dissection of CHD7 Functions in Eye Development and the Molecular Basis for Ocular Defects in CHARGE Syndrome. Invest Ophthalmol Vis Sci 56:7923-30
Gage, Philip J; Kuang, Chen; Zacharias, Amanda L (2014) The homeodomain transcription factor PITX2 is required for specifying correct cell fates and establishing angiogenic privilege in the developing cornea. Dev Dyn 243:1391-400
French, Curtis R; Seshadri, Sudha; Destefano, Anita L et al. (2014) Mutation of FOXC1 and PITX2 induces cerebral small-vessel disease. J Clin Invest 124:4877-81
Plageman Jr, Timothy F; Zacharias, Amanda L; Gage, Phillip J et al. (2011) Shroom3 and a Pitx2-N-cadherin pathway function cooperatively to generate asymmetric cell shape changes during gut morphogenesis. Dev Biol 357:227-34
Zacharias, Amanda L; Lewandoski, Mark; Rudnicki, Michael A et al. (2011) Pitx2 is an upstream activator of extraocular myogenesis and survival. Dev Biol 349:395-405

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