Cathepsin G, acid phosphatase, and alpha 1-proteinase inhibitor messenger RNA levels in keratoconus corneas.
OBJECTIVE
Keratoconus is characterized by thinning and scarring of the central region of the cornea. The authors have shown, in corneas obtained from patients with keratoconus, that lysosomal enzyme activities are elevated, whereas levels of protease inhibitors such as alpha 1-proteinase inhibitor (alpha 1-PI) are reduced. This study was undertaken to examine further the gene expression of cathepsin G, acid phosphatase, and alpha 1-PI in keratoconus corneas.


METHODS
Corneal buttons were collected from patients with keratoconus, normal subjects, and patients with other corneal diseases. In situ hybridization was performed on paraffin sections using a tritium-labeled probe for cathepsin G or alpha 1-PI. Competitive polymerase chain reaction (PCR) was used to determine the messenger RNA (mRNA) levels for lysosomal acid phosphatase and alpha 1-PI in epithelial and stromal cells of keratoconus corneas.


RESULTS
Silver grains, indicative of positive in situ hybridization products, were observed in all three cell types of normal corneas for both DNA probes. Compared with normal and other diseased controls, the labeling was enhanced for cathepsin G but was diminished for alpha 1-PI in the epithelium of keratoconus corneas. Competitive PCR showed that the mRNA level for acid phosphatase was higher and that the mRNA level for alpha 1-PI was lower in keratoconus corneas.


CONCLUSIONS
These results indicate that the mRNA level for degradative enzymes in increased and that for alpha 1-PI it is reduced in keratoconus corneas. This study provides the first evidence that the altered expression of multiple enzymes and inhibitors in keratoconus occurs at the gene level. Furthermore, it implicates a possible role of coordinated transcriptional regulation of gene expressions in keratoconus.
Whitelock
R B
RB
Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago College of Medicine 60612, USA.
Fukuchi
T
T
Zhou
L
L
Twining
S S
SS
Sugar
J
J
Feder
R S
RS
Yue
B Y
BY
D000135:Acid Phosphatase / Q000235:genetics*; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D056649:Cathepsin G; D002403:Cathepsins / Q000235:genetics*; D002648:Child; D002675:Child, Preschool; D003315:Cornea / Q000378:metabolism*; D017931:DNA Primers / Q000737:chemistry; D015342:DNA Probes; D004587:Electrophoresis, Agar Gel; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D017403:In Situ Hybridization; D007640:Keratoconus / Q000378:metabolism*; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000378:metabolism*; D012697:Serine Endopeptidases / Q000235:genetics*; D015842:Serine Proteinase Inhibitors / Q000235:genetics*; D000515:alpha 1-Antitrypsin / Q000235:genetics*
D017931:DNA Primers; D015342:DNA Probes; D012333:RNA, Messenger; D015842:Serine Proteinase Inhibitors; D000515:alpha 1-Antitrypsin; D000135:Acid Phosphatase; D002403:Cathepsins; D012697:Serine Endopeptidases; C534094:CTSG protein, human; D056649:Cathepsin G