Abstract
Purpose: :
Dysregulation of microRNAs (miRNAs) has been implicated in various fibrotic conditions and in the pathophysiology of glaucoma. To determine the role of miRNAs in pseudoexfoliation (PEX) syndrome, a stress-induced elastic microfibrillopathy and a major risk factor for glaucoma, we examined the expression profile of miRNAs in ocular tissues from PEX and control patients.
Methods: :
Iridal and ciliary tissue specimens were obtained from donor eyes with PEX syndrome and age-matched normal donor eyes. miRNAs were isolated using the miRNeasy kit and subjected to quality control by the Human RT2 QC PCR array. Iridal specimens were analyzed for 88 different miRNAs using the Human RT2 Profiler miRNA Finder PCR Array. The differential expression of miRNAs was verified by specific miRNA real-time PCR assays in iridal and ciliary specimens. Computational analysis of potential miRNA target sequences in mRNAs of major constituents of PEX material as well as key components of the TGF-ß1 signaling pathway was carried out using the TargetScan and MiRanda algorithms.
Results: :
PCR-Array analysis revealed increased levels of 15 miRNAs and decreased levels of 4 miRNAs in tissue specimens from patients with PEX syndrome as compared to normal donor eyes (n=3 for each group). Quantitative real-time PCR confirmed a 3-fold increase of mir-96 and a 2-fold decrease of mir-29a, -29b, -29c and mir-32 in iridal and ciliary body tissue specimens from PEX patients (n=6). Computational analysis predicted several target sequences for mir-29a, -29b, -29c, and mir-32 in the 3' untranslated region (3'-UTR) of fibrillin-1 and elastin, two main components of PEX material, whereas mir-96 targets SMAD-7, a known inhibitor of TGF-ß1 signaling.
Conclusions: :
Our data suggest that dysregulated expression of miRNAs may play a pathophysiological role in the abnormal matrix metabolism characteristic of PEX syndrome. In view of the predicted target sequences of these miRNAs, the downregulation of mir-29a, -29b, -29c and mir-32 may contribute to the increased expression of fibrillin-1 and elastin in ocular tissues of PEX patients, whereas the upregulation of mir-96 may lead to increased TGF-ß1 activity through targeting the inhibitory SMAD-7.
Keywords: extracellular matrix • gene/expression • gene modifiers