Effects of Sp1 overexpression on cultured human corneal stromal cells.
Sp1, a transcription factor, is upregulated in keratoconus, a cornea-thinning disease. Keratoconus corneas have also been shown to contain increased levels of degradative enzymes such as cathepsin B and decreased proteinase inhibitors such as alpha1-proteinase inhibitor (alpha1-PI). We transfected cultured human corneal stromal cells to overexpress Sp1. The resulting effects on cathepsin B and alpha1-PI levels as well as the cellular proliferative and apoptotic activities were examined by Western blotting and cytochemical staining. It was found that the Sp1 transfected cells contained a greater amount of cathepsin B than did mock transfected controls. The activity of cathepsin B was also increased. By contrast, the protein level of alpha1-PI was lowered in corneal stromal cells upon Sp1 overexpression. The Sp1-induced alterations thus mimicked closely those observed in keratoconus, supporting the notion that Sp1 upregulation may be a key factor contributing directly to the disease development. Furthermore, the apoptotic activity was unaffected in Sp1 transfectants but the proliferation was inhibited, consistent with the idea that Sp1 may play a role in differentiation of corneal cells.
Shen
Xiang
X
Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago College of Medicine, Chicago, IL, USA.
Park
Jeong-Seok
JS
Qiu
Ye
Y
Sugar
Joel
J
Yue
Beatrice Y J T
BY
D000293:Adolescent; D000328:Adult; D017209:Apoptosis; D015153:Blotting, Western; D002401:Cathepsin B / Q000378:metabolism; D049109:Cell Proliferation; D002478:Cells, Cultured; D002648:Child; D003315:Cornea / Q000166:cytology*; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D019394:Ki-67 Antigen / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016329:Sp1 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D017154:Stromal Cells / Q000166:cytology / Q000378:metabolism*; D014162:Transfection; D055815:Young Adult; D000515:alpha 1-Antitrypsin / Q000378:metabolism
D019394:Ki-67 Antigen; D011993:Recombinant Fusion Proteins; D016329:Sp1 Transcription Factor; D000515:alpha 1-Antitrypsin; D049452:Green Fluorescent Proteins; D002401:Cathepsin B