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Chi-Chin Sun, Yi-Fang Lin, Hsiao-Ting Chiu, Kuo-Ying Lee, Jong-Hwei Pang Su; A Novel Function Of Beta 1 Integrin In Mediating Apoptosis Of Ex Vivo Expanded Human Limbal Epithelial Cells. Invest. Ophthalmol. Vis. Sci. 2011;52(14):528.
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To investigate the expression of β1 integrin and its novel pro-apoptotic function in human corneas and ex vivo expanded limbal epithelial cells.
Corneoscleral buttons from human donor eyes were cultured on intact amniotic membrane (AM) or culture dishes for 3 weeks. Expression of β1 integrin, caspase-3 and interleukin 1 receptor antagonist (IL-1RA) in human corneas or expanded limbal epithelial cells was determined by immunofluorescent staining, Western blotting, reverse transcription-polymerase chain reaction (RT-PCR) and real-time PCR. Apoptosis of ex vivo expanded limbal epithelial cells was assessed by Annexin V-fluorescein isothiocyanate staining.
β1 integrin was positively stained in both intact AM-expanded limbal epithelial cells and human corneas. However, cytoplasmic localization of β1 integrin was noted in superficial layer epithelial layer of human central and limbal corneas. Down-regulation of β1 integrin in limbal cultures on intact AM than on plastic dishes at both transcriptional and translational levels was confirmed by RT-PCR, real-time PCR, immunofluorescent staining and Western blotting analyses. Histological sections of human central and limbal corneas demonstrated that caspase-3, co-localized with cytoplasmic β1 integrin, was also preferentially expressed at superficial epithelial cell layers. Co-localization of caspase-3 and β1 integrin was found in limbal epithelial outgrowth on plastic dishes. In addition, neutralization of β1 integrin not only reduced apoptosis of limbal epithelial cells cultured on plastic dishes, but also induced IL-1RA mRNA transcripts as evidenced by real-time PCR.
These results implicated that cytoplasmic β1 integrin is involved in integrin-mediated apoptosis in ex vivo expanded limbal epithelial cells.
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