Abstract
Purpose: :
MicroRNAs (miRNA) are small, endogenously expressed non-coding RNAs that negatively regulate expression of protein-coding genes. Recent evidence has suggested a critical role for miRNAs during development and cell differentiation. To examine the function of miRNAs in mouse corneal development, we characterized the expression profiles of miRNAs in the developing mouse cornea at postnatal day (PN) 9 and in the mature cornea at 6 weeks after birth.
Methods: :
miRNA arrays were performed on PN9 and adult mouse (6-week-old) corneas. The validity of selected microRNA expression profiles were confirmed by qRT-PCR. A simultaneous profiling of mRNA expression was also performed by microarrays to search for candidate mRNA targets for the miRNAs.
Results: :
Of the 568 verified mouse miRNAs, 75 demonstrated at least 2-fold difference in expression between PN9 and adult mouse cornea. Among the top 50 abundant corneal miRNAs, 15 were differentially expressed in PN9 and adult cornea. In particular, mir-184, mir-204, mir-205, and mir-31 were up-regulated at least 5-fold in adult relative to PN9 cornea. By contrast, expression of mir-214 was down-regulated 7.5-fold in adult cornea. Many of the differentially expressed miRNAs, such as mir-31 and mir-181, have been previously shown to be involved in regulation of cell cycle progression and/or cell differentiation. Analysis of mRNA expression profile revealed that a significant number of cell cycle genes were differentially expressed (mostly down-regulated) during corneal development.
Conclusions: :
Our data demonstrate dynamic changes of miRNA expression in cornea after eye opening and corneal epithelial stratification. The differentially expressed miRNAs may play important roles during corneal development, particularly in regulation of cell proliferation and differentiation.
Keywords: gene/expression • gene microarray • differentiation