Role of ErbB2 in Corneal Epithelial Wound Healing.

Invest Ophthalmol Vis Sci

Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta, Georgia.

Published: December 2004

AI Article Synopsis

  • The study investigates the role of erbB2 in cell migration related to EGF receptor (EGFR) activation in human corneal epithelial cells (HCECs) by functionally depleting erbB2 using a specific retrovirus.
  • After confirming the depletion of erbB2, the researchers found that while wounding increased EGFR phosphorylation, it did not trigger erbB2 phosphorylation in the erbB2-depleted cells.
  • The results showed that loss of functional erbB2 impaired cell migration and wound healing in response to HB-EGF, suggesting erbB2 is crucial for effective EGF receptor-mediated responses.

Article Abstract

Purpose: Human corneal epithelial cells (HCECs) were functionally depleted of erbB2 to elucidate its role in epidermal growth factor (EGF) receptor (EGFR) activation-dependent cell migration.

Methods: The retrovirus pBabe-5R, which encodes an erbB2 single-chain antibody with an endoplasmic reticulum (ER)-targeting sequence, and control pBabe-puro were used to infect THCE cells (an SV40-immortalized HCEC line). Several cell lines expressing 5R were selected along with a pBabe-puro control line. The depletion of erbB2 was verified by cell surface biotinylation of proteins, followed by streptavidin precipitation and subsequent detection of erbB2 by immunoblot analysis. Activation of erbBs was analyzed by immunoprecipitation using the phosphotyrosine antibody pY20, followed by Western blot analysis with erbB1 or erbB2 antibodies. Phosphorylation of extracellular signal-regulated kinase (ERK) and phosphatidylinositol 3'-kinase (PI3K) was analyzed by Western blot with antibodies specific to phosphorylated proteins. Effects of erbB2 depletion on heparin-binding EGF-like growth factor (HB-EGF)-induced cell migration were determined by Boyden chamber migration assay and by scratch wound assay.

Results: Wounding induced erbB2 tyrosine phosphorylation. Expression of 5R encoding an erbB2 single-chain antibody with an endoplasmic reticulum-targeting sequence depleted the cell surface expression of erbB2 in HCECs. Wounding resulted in a rapid increase in the phosphorylation of erbB1 in both 5R-expressing and control cells, whereas wound-induced erbB2 phosphorylation in 5R-expressing cells was not detectable. Depletion of functional erbB2 attenuated the healing of scratch wounds in the presence of HB-EGF and impaired both chemotactic migration stimulated by HB-EGF and haptotactic migration toward a fibronectin-collagen I (3:1; FNC) coating mix. Expression of 5R affected both the intensity and the duration of wound-induced, EGFR-elicited ERK and PI3K activation. Inhibition of ERK and PI3K pathways in cultured porcine corneas impaired ex vivo epithelial wound healing.

Conclusions: ErbB2 serves as a critical component that couples erbB receptor tyrosine kinase to the migration machinery of corneal epithelial cells.

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Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2666385PMC
http://dx.doi.org/10.1167/iovs.04-0119DOI Listing

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