Transactivation of EGFR mediates insulin-stimulated ERK1/2activation and enhanced cell migration in human corneal epithelialcells

[摘要] Purpose: Insulin activates phosphatidylinositol 3-kinase (PI3K) andextracellular signal-regulated kinase (ERK)-1/2 in human cornealepithelial cells. These events have been shown to be involved in woundhealing. However, the mechanism of insulin-induced ERK pathway is notclear during corneal wound healing. In this study, the effect of insulinassociated with epidermal growth factor receptor (EGFR) on wound healingin transformed human corneal epithelial cells was investigated todetermine the signaling mechanism involved.Methods: SV40-immortalized human corneal epithelial (THCE) cellswere cultured on a diluted Matrigel matrix that resembled the basementmembrane of the corneal epithelium. A wound was introduced with amicropipette tip, and closure of the scratch wound was photographed 12 hafter exposure to insulin. Activation of EGFR was analyzed byimmunoprecipitation, and cytoskeletal rearrangements were visualizedwith rhodamine-conjugated phalloidin.Results: Exposure of corneal epithelial cells to insulin inducedphosphorylation of EGFR. Inhibition of EGFR activation by AG1478 or theMMP inhibitor, GM6001, reduced phosphorylation of insulin-induced ERK inthe presence of insulin and delayed wound closure. In addition, cellsexposed to insulin contained stress fibers and their submembranouscortical actin was depleted. These effects were inhibited by AG1478.Conclusions: Inhibition of EGFR activity decreases cell migrationinvolved in insulin-induced wound repair, an effect that mimicsinhibition of MMP activation. Inhibition of MMP activity leads todecreased EGFR phosphorylation. Our data show that insulin stimulateswound healing in the corneal epithelium by activating EGFR, and point toa novel insulin signaling pathway that acts during corneal woundhealing.

[学科分类] 生物化学/生物物理