Plasminogen activator inhibitor-1 mRNA is localized in the ciliary epithelium of the rodent eye.
OBJECTIVE
To identify in the adult and developing rodent eye cells expressing the gene encoding plasminogen activator inhibitor-1 (PAI-1), an important component of the fibrinolytic system.


METHODS
PAI-1 mRNA was localized in cryostat thin eye sections via in situ hybridization analysis using specific 35S-labeled riboprobes. PAI-1 activity was tested in the aqueous humor using one-phase reverse zymography.


RESULTS
In the adult eye, PAI-1 mRNA was detected exclusively in epithelial cells of the ciliary processes, primarily in the apexes. In addition, PAI-1 activity was detected in the aqueous humor. PAI-1 mRNA was first found in the ciliary epithelium in embryonic day 18.5, when the ciliary body has reached an advanced developmental stage. PAI-1 mRNA was also detected in the ganglion cell layer of the retina at postnatal days 1 to 4, when angiogenesis takes place.


CONCLUSIONS
During development, PAI-1 is likely to be involved in retina vascularization, in agreement with other cases of angiogenesis. Results for the adult eye indicate that the ciliary epithelium is the source for PAI-1 activity found in the aqueous humor. The results suggest that PAI-1 plays a role in balancing fibrinolysis and proteolysis specifically in the anterior segment of the eye, implying that PAI-1 overproduction in the ciliary epithelium could shift the balance against proteolysis and thus may interfere with aqueous outflow.
Masos
T
T
Department of Biological Chemistry, the Weizmann Institute of Science, Rehovot, Israel.
Dan
J A
JA
Miskin
R
R
D000818:Animals; D000831:Animals, Newborn / Q000378:metabolism; D001082:Aqueous Humor / Q000378:metabolism; D002924:Ciliary Body / Q000254:growth & development / Q000378:metabolism*; D004847:Epithelial Cells / Q000378:metabolism*; D005260:Female; D015870:Gene Expression; D017403:In Situ Hybridization; D051379:Mice; D008817:Mice, Mutant Strains; D017395:Plasminogen Activator Inhibitor 1 / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D012165:Retinal Ganglion Cells / Q000378:metabolism; D010959:Tissue Plasminogen Activator / Q000378:metabolism
D017395:Plasminogen Activator Inhibitor 1; D012333:RNA, Messenger; D010959:Tissue Plasminogen Activator