Integrins in slow-cycling corneal epithelial cells at the limbus in the mouse.
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 alpha9-integrin is present in a subset of the basal cells at the corneal limbus and absent in the central cornea, beta1-, beta4-, alpha3-, and alpha6-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 (alpha9, beta1, and beta4) 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 alpha9-integrin-positive cells, most LRCs were alpha9-integrin-negative and expressed high levels of beta1- and beta4-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 beta1- and beta4-integrin and little alpha9-integrin.
Pajoohesh-Ganji
Ahdeah
A
Department of Anatomy and Cell Biology, The George Washington University Medical Center, 2300 I Street NW, Washington, DC 20037, USA.
Pal-Ghosh
Sonali
S
Simmens
Samuel J
SJ
Stepp
Mary Ann
MA
D000818:Animals; D001973:Bromodeoxyuridine / Q000378:metabolism; D002453:Cell Cycle; D019573:Epithelium, Corneal / Q000166:cytology* / Q000378:metabolism*; D039001:Integrin alpha Chains / Q000378:metabolism; D039422:Integrin alpha3 / Q000378:metabolism; D039503:Integrin alpha6 / Q000378:metabolism; D019012:Integrin beta1 / Q000378:metabolism; D039663:Integrin beta4 / Q000378:metabolism; D016023:Integrins / Q000378:metabolism*; D016850:Limbus Corneae / Q000166:cytology* / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D018613:Microscopy, Confocal; D008954:Models, Biological; D011419:Propidium; D013234:Stem Cells / Q000166:cytology* / Q000378:metabolism*
D039001:Integrin alpha Chains; D039422:Integrin alpha3; D039503:Integrin alpha6; D019012:Integrin beta1; D039663:Integrin beta4; D016023:Integrins; C084613:integrin alpha9; D011419:Propidium; D001973:Bromodeoxyuridine