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Invest Ophthalmol Vis Sci. 2014 Jul 1;55(8):4691-9. doi: 10.1167/iovs.14-14133.

Antagonizing c-Cbl enhances EGFR-dependent corneal epithelial homeostasis.

Author information

1
Department of Pharmacology and Toxicology, University of Louisville, Louisville, Kentucky, United States.
2
Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma, United States.
3
Department of Pharmacology and Toxicology, University of Louisville, Louisville, Kentucky, United States Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma, United States.

Abstract

PURPOSE:

In many cell types, the E3 ubiquitin ligase, c-Cbl, induces ligand-dependent ubiquitylation of the epidermal growth factor receptor (EGFR) and targets the receptor for lysosomal degradation. The goal of this study was to determine whether c-Cbl is a negative regulator of EGFR in the corneal epithelium and if it can be inhibited to promote corneal epithelial homeostasis.

METHODS:

Expression and activity of c-Cbl were blocked in immortalized human corneal epithelial cells (hTCEpi) using RNAi and pharmacological agents ([4-amino-5-(4-methylphenyl)-7-(t-butyl)pyrazolo-d-3,4-pyrimidine] or PP1). Following c-Cbl inhibition, cells were assessed for ligand-dependent receptor ubiquitylation, receptor phosphorylation, and in vitro wound healing. Subsequent experiments used PP1 in hTCEpi cells and monitored in vivo murine corneal epithelial wound healing.

RESULTS:

Knockdown and inhibition of c-Cbl decreased ligand-dependent ubiquitylation of the EGFR and prolonged receptor activity as measured by tyrosine phosphorylation. Further, these treatments also increased the extent of ligand-dependent corneal epithelial wound healing in vitro and in vivo.

CONCLUSION:

Manipulating the duration of EGFR activity can enhance the rate of restoration of the corneal epithelial layer. Based on our findings, c-Cbl is a new therapeutic target to enhance EGFR-mediated corneal epithelial homeostasis that bypasses the limitations of previous approaches.

KEYWORDS:

EGFR; corneal epithelium; corneal wound healing; endocytic trafficking

PMID:
24985478
PMCID:
PMC4120408
DOI:
10.1167/iovs.14-14133
[Indexed for MEDLINE]
Free PMC Article

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