Rapid healing of the corneal epithelium in response to injury is essential for maintenance of its barrier function. The long-term goal of the laboratory is to obtain basic information about the molecular and cell biology of corneal wound healing. Recent data demonstrated that a greatly elevated expression of amyloid b/A4 precursor-like protein (APLP2) correlates with post-wound corneal re-epithelization and that cells overexpressing APLP2 have enhanced migration over extracellular matrix (ECM) proteins. APLP2 is very closely related to the amyloid b/A4 precursor protein of Alzheimer's disease. During corneal wound healing, the ectodomain of APLP2 is shed by migrating epithelial cells, and incorporated into the wound bed around the leading edge. The Kunitz type serine proteinase inhibitor domain (KPI) of APLP2 inhibits an uncharacterized proteinase and blocks epithelial wound closure in corneal organ culture. APLP2 in the cornea is modified by addition of chrondroitin sulfate chains. These data suggest that APLP2 plays a role(s) in corneal wound repair. The current proposal will test the hypotheses that APLP2 controls erine proteinase activity, mediates cell adhesion, and promotes cell migration during corneal re-epithelialization. (i) The mechanism by which growth factors regulate synthesis and shedding of APLP2 in corneal epithelial cells will be evaluated by metabolic labeling and Western blotting; the involvement of both protein kinase C and tyrosine phosphorylation dependent signal transduction pathways in APLP2 shedding will be investigated using specific blocking reagents. (ii) The mechanism by which APLP2 mediates epithelial cell adhesion and migration will be assessed using several methods including purification of APLP2 isoforms, cDNA transfection and expression of chimeric APLP2 proteins that are resistant to proteolytic cleavage, and in vitro cell adhesion and cell migration assays. In particular, the role of ectodomain shedding of APLP2 as a means to break adhesion and to facilitate cell migration, and of ECM-associated APLP2 in epithelial cell adhesion and migration will be investigated. (iii) The identify of proteinase(s) that is inhibited by KPI containing APLP2 will be determined using affinity purification and cDNA cloning, and the role of the interplay of this proteinase and APLP2 in the growth factor processing will be elucidated using organ culture and an in vitro cell-free assay. These experiments will provide the basis to begin constructing a detailed map of the molecular pathways and interconnecting networks of proteins functioning in wound repair and to develop therapeutics for treatment of corneal diseases like recurrent erosions and persistent defects of the epithelium.

National Institute of Health (NIH)
National Eye Institute (NEI)
Research Project (R01)
Project #
Application #
Study Section
Visual Sciences A Study Section (VISA)
Program Officer
Fisher, Richard S
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Schepens Eye Research Institute
United States
Zip Code
Han, Jing; Li, Yue; Liu, Xiuli et al. (2018) Metformin suppresses retinal angiogenesis and inflammation in vitro and in vivo. PLoS One 13:e0193031
Cui, Xinhan; Gao, Nan; Me, Rao et al. (2018) TSLP Protects Corneas From Pseudomonas aeruginosa Infection by Regulating Dendritic Cells and IL-23-IL-17 Pathway. Invest Ophthalmol Vis Sci 59:4228-4237
Sun, Haijing; Lee, Patrick; Yan, Chenxi et al. (2018) Inhibition of Soluble Epoxide Hydrolase 2 Ameliorates Diabetic Keratopathy and Impaired Wound Healing in Mouse Corneas. Diabetes 67:1162-1172
Gao, Nan; Me, Rao; Dai, Chenyang et al. (2018) Opposing Effects of IL-1Ra and IL-36Ra on Innate Immune Response to Pseudomonas aeruginosa Infection in C57BL/6 Mouse Corneas. J Immunol 201:688-699
Ross, Bing X; Gao, Nan; Cui, Xinhan et al. (2017) IL-24 Promotes Pseudomonas aeruginosa Keratitis in C57BL/6 Mouse Corneas. J Immunol 198:3536-3547
Dong, Chen; Gao, Nan; Ross, Bing X et al. (2017) ISG15 in Host Defense Against Candida albicans Infection in a Mouse Model of Fungal Keratitis. Invest Ophthalmol Vis Sci 58:2948-2958
Gao, Nan; Liu, Xiaowei; Wu, Jiayin et al. (2017) CXCL10 suppression of hem- and lymph-angiogenesis in inflamed corneas through MMP13. Angiogenesis 20:505-518
Zhang, Xilin; Liu, Queping; Wang, Jie et al. (2016) TIM-4 is differentially expressed in the distinct subsets of dendritic cells in skin and skin-draining lymph nodes and controls skin Langerhans cell homeostasis. Oncotarget 7:37498-37512
Yan, Chenxi; Gao, Nan; Sun, Haijing et al. (2016) Targeting Imbalance between IL-1? and IL-1 Receptor Antagonist Ameliorates Delayed Epithelium Wound Healing in Diabetic Mouse Corneas. Am J Pathol 186:1466-80
Gao, Nan; Yan, Chenxi; Lee, Patrick et al. (2016) Dendritic cell dysfunction and diabetic sensory neuropathy in the cornea. J Clin Invest 126:1998-2011

Showing the most recent 10 out of 71 publications