The long-term goal of this project is to elucidate the molecular determinants of the regulation of corneal epithelial cell phenotype. It is now apparent that corneal epithelial cell phenotype must be held in check by constant transcriptional maintenance, or it may suffer reprogramming to alternate epithelial fates. While many specific genetic and environmental causes can trigger this change, the final result is consistent and catastrophic for vision. In this current proposal I present plans to study the nuclear protein pinin (Pnn). Our recent data indicate that silencing of the gene for Pnn during development results in a loss of normal corneal epithelial features and the change to a keratinizing epithelium. These data have taken our studies to an exciting new direction involving the exploration of Pnn as a key regulator of specific epithelial identity. We now present plans to define the consequences of pnn deletion in the mature corneal epithelial integrity by constructing inducible knockouts. Using these animals, we wish to characterize the impact of pnn deletions on the limbal stem cell compartment. We will also explore the relationship of Pnn and Pax6 in the genetic regulation/reprogramming of cell fate differentiation decision of the corneal epithelium. Finally, we will elucidate the relationship of Pnn deletion to Wnt pathway activation and maintenance of epithelial cell identity, by investigating beta-catenin activation and the involvement of a Pnn-partner, RNA helicase p68, in this process. The three proposed aims address fundamental issues of corneal epithelial biology and will provide a new window into the molecular processes by which epithelial identity is established and maintained by the corneal epithelium. Studies addressing how the corneal epithelial identity is established and maintained are central to vision research and resolving these molecular details and pathways pertaining to these processes will contribute significantly to the design of new therapies to impact the maintenance and repair of the corneal epithelial phenotype and the corneal epithelium physiology and barrier.

Public Health Relevance

Many severe ocular surface diseases result in the loss of the corneal epithelial phenotype, whereby the epithelium undergoes a squamous metaplasia leading to severe visual loss and blindness. Our recent data implicates a protein under study in our laboratory, Pnn, as a key contributor to the establishment and maintenance of the corneal epithelial identity. Investigation of the role of Pnn in these fundamentally important processes will discover key information that may enable us to avoid epithelial transdifferentiation and/or reverse those that have occurred.

National Institute of Health (NIH)
National Eye Institute (NEI)
Research Project (R01)
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Anterior Eye Disease Study Section (AED)
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Mckie, George Ann
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University of Florida
Anatomy/Cell Biology
Schools of Medicine
United States
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Akin, Debra; Newman, Jeremy R B; McIntyre, Lauren M et al. (2016) RNA-seq analysis of impact of PNN on gene expression and alternative splicing in corneal epithelial cells. Mol Vis 22:40-60
Joo, Jeong Hoon; Ryu, Danny; Peng, Qian et al. (2014) Role of Pnn in alternative splicing of a specific subset of lncRNAs of the corneal epithelium. Mol Vis 20:1629-42
Joo, Jeong-Hoon; Correia, Greg P; Li, Jian-Liang et al. (2013) Transcriptomic analysis of PNN- and ESRP1-regulated alternative pre-mRNA splicing in human corneal epithelial cells. Invest Ophthalmol Vis Sci 54:697-707
Xu, Yufei; Xu, Chao; Kato, Akiko et al. (2012) Tet3 CXXC domain and dioxygenase activity cooperatively regulate key genes for Xenopus eye and neural development. Cell 151:1200-13
Joo, Jeong-Hoon; Taxter, Timothy J; Munguba, Gustavo C et al. (2010) Pinin modulates expression of an intestinal homeobox gene, Cdx2, and plays an essential role for small intestinal morphogenesis. Dev Biol 345:191-203
Joo, Jeong-Hoon; Kim, Yong H; Dunn, Nicholas W et al. (2010) Disruption of mouse corneal epithelial differentiation by conditional inactivation of pnn. Invest Ophthalmol Vis Sci 51:1927-34
Alpatov, Roman; Shi, Yujiang; Munguba, Gustavo C et al. (2008) Corepressor CtBP and nuclear speckle protein Pnn/DRS differentially modulate transcription and splicing of the E-cadherin gene. Mol Cell Biol 28:1584-95
Joo, Jeong-Hoon; Lee, Young Jae; Munguba, Gustavo C et al. (2007) Role of Pinin in neural crest, dorsal dermis, and axial skeleton development and its involvement in the regulation of Tcf/Lef activity in mice. Dev Dyn 236:2147-58
Joo, Jeong-Hoon; Alpatov, Roman; Munguba, Gustavo C et al. (2005) Reduction of Pnn by RNAi induces loss of cell-cell adhesion between human corneal epithelial cells. Mol Vis 11:133-42
Alpatov, Roman; Munguba, Gustavo Costa; Caton, Paul et al. (2004) Nuclear speckle-associated protein Pnn/DRS binds to the transcriptional corepressor CtBP and relieves CtBP-mediated repression of the E-cadherin gene. Mol Cell Biol 24:10223-35

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