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Xiaowen Lu, Mitchell A Watsky; Gap Junction Diffusion Coefficients in Mouse Cornea Epithelium and Keratocytes. Invest. Ophthalmol. Vis. Sci. 2014;55(13):5505.
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Gap junctions are present in all corneal cell types and have been shown to play a critical role in cell phenotype determination. This study measured and compared gap junction diffusion coefficients among the different cornea epithelium phenotypes and in keratocytes using a non-invasive technique, fluorescence recovery after photobleaching (FRAP). Previous gap junction studies in cornea epithelium and keratocytes were performed using cultured cells or ex vivo invasive techniques. These invasive techniques were unable to measure diffusion coefficients and were likely disruptive to normal cell physiology.
Corneas from mice were stained with 5(6)-carboxyflluorescein diacetate. Gap junction diffusion coefficients of central versus peripheral corneal epithelium, limbal cells, and keratocytes residing in intact corneas were measured using FRAP.
Diffusion coefficients equaled 18.71, 9.81, 5.60, and 2.76 μm2/s for superficial squamous cells, middle wing cells, basal cells, and keratocytes, respectively. The diffusion coefficients of superficial cells located in the center of cornea were higher than those located along the periphery of the cornea.
Our results demonstrate differences in gap junction dye spread among the epithelial cell phenotypes. This is the first study to demonstrate functional gap junctions in the superficial cornea epithelium. Central superficial cells had higher diffusion coefficients than peripheral cells. Furthermore, gap junction diffusion coefficient values changed along the developmental axis of corneal epithelium, increasing from basal cells to wing cells to squamous cells, following the centripetal migration pattern and vertical movement of cells from the stroma to the surface.
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