MicroRNAs are powerful gene expression regulators, but their corneal repertoire and potential changes in
corneal diseases remain unknown. Our purpose was to identify
miRNAs altered in the human diabetic cornea by microarray analysis, and to examine their effects on wound healing in cultured
telomerase-immortalized human corneal epithelial cells (
HCEC) in vitro. Total
RNA was extracted from age-matched human autopsy normal (n=6) and diabetic (n=6) central corneas, Flash Tag end-labeled, and hybridized to Affymetrix® GeneChip®
miRNA Arrays. Select
miRNAs associated with diabetic cornea were validated by quantitative RT-PCR (Q-PCR) and by in situ hybridization (ISH) in independent samples.
HCEC were transfected with human pre-miR™miRNA precursors (h-miR) or their inhibitors (
antagomirs) using
Lipofectamine 2000. Confluent transfected cultures were scratch-wounded with P200 pipette tip.
Wound closure was monitored by digital photography. Expression of signaling
proteins was detected by immunostaining and Western blot. Using microarrays, 29
miRNAs were identified as differentially expressed in diabetic samples. Two
miRNA candidates showing the highest fold increased in expression in the diabetic cornea were confirmed by Q-PCR and further characterized.
HCEC transfection with h-miR-146a or h-miR-424 significantly retarded
wound closure, but their respective
antagomirs significantly enhanced wound healing vs. controls. Cells treated with h-miR-146a or h-miR-424 had decreased p-p38 and p-EGFR staining, but these increased over control levels close to the
wound edge upon
antagomir treatment. In conclusion, several
miRNAs with increased expression in human diabetic central corneas were found. Two such
miRNAs inhibited cultured corneal epithelial cell wound healing. Dysregulation of
miRNA expression in human diabetic cornea may be an important mediator of abnormal wound healing.