Integrins in Slow-Cycling Corneal Epithelial Cells at the Limbus in the Mouse

Authors

  • Ahdeah Pajoohesh-Ganji,

    1. Departments of Anatomy and Cell Biology, The George Washington University Medical Center, Washington, DC, USA
    2. Department of Biological Sciences, The George Washington University Medical Center, Washington, DC, USA
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  • Sonali Pal-Ghosh,

    1. Departments of Anatomy and Cell Biology, The George Washington University Medical Center, Washington, DC, USA
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  • Samuel J. Simmens,

    1. Departments of Epidemiology and Biostatistics, The George Washington University Medical Center, Washington, DC, USA
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  • Mary Ann Stepp Ph.D.

    Corresponding author
    1. Departments of Anatomy and Cell Biology, The George Washington University Medical Center, Washington, DC, USA
    2. Department of Ophthalmology, The George Washington University Medical Center, Washington, DC, USA
    • Departments of Anatomy and Cell Biology and Ophthalmology, The George Washington University Medical Center, 2300 I Street NW, Washington, DC 20037, USA. Telephone: 202-994-0557; Fax: 202-994-8885
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Abstract

Adult corneal epithelial stem cells (CESCs) have been shown to reside at the periphery of the cornea at a site called the corneoscleral junction or limbus. Although studies have shown that these cells are slow cycling, their molecular characteristics are not well understood. Using a whole-mount procedure, we show that whereas α9-integrin is present in a subset of the basal cells at the corneal limbus and absent in the central cornea, β1-, β4-, α3-, and α6-integrins are more highly expressed overall in central corneal basal cells. To characterize CESCs based on their slow-cycling nature, we simultaneously evaluated 5-bromo-2-deoxyuridine (BrdU) label-retaining cells (LRCs) and integrin expression (α9, β1, and β4) in a total of 1,889 cells at the limbus of adult mice that had been injected as neonates with BrdU. Whereas the LRCs were usually observed adjacent to α9-integrin-positive cells, most LRCs were α9-integrin–negative and expressed high levels of β1- and β4-integrin. In addition, we observed more BrdU-positive LRCs at the superior and inferior quadrants of adult mouse corneas than at the nasal and temporal quadrants, and determined that 0.94 to 3.6% of the limbal basal cells were slow cycling. We conclude from these data that the slow-cycling LRCs in the adult mouse cornea are enriched in cells that express high levels of β1- and β4-integrin and little α9-integrin.

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