title: Scleral micro-RNA signatures in adult and fetal eyes.
abstract: BACKGROUND
  In human eyes, ocular enlargement/growth reflects active extracellular matrix remodeling of the outer scleral shell. Micro-RNAs are small non-coding RNAs that regulate gene expression by base pairing with target sequences. They serve as nodes of signaling networks. We hypothesized that the sclera, like most tissues, expresses micro-RNAs, some of which modulate genes regulating ocular growth. In this study, the scleral micro-RNA expression profile of rapidly growing human fetal eyes was compared with that of stable adult donor eyes using high-throughput microarray and quantitative PCR analyses.
  
  
  METHODS
  Scleral samples from normal human fetal (24 wk) and normal adult donor eyes were obtained (n=4 to 6, each group), and RNA extracted. Genome-wide micro-RNA profiling was performed using the Agilent micro-RNA microarray platform. Micro-RNA target predictions were obtained using Microcosm, TargetScan and PicTar algorithms. TaqMan® micro-RNA assays targeting micro-RNAs showing either highest significance, detection, or fold differences, and collagen specificity, were applied to scleral samples from posterior and peripheral ocular regions (n=7, each group). Microarray data were analyzed using R, and quantitative PCR data with 2^-deltaCt methods.
  
  
  RESULTS
  Human sclera was found to express micro-RNAs, and comparison of microarray results for adult and fetal samples revealed many to be differentially expressed (p<0.01, min p= 6.5x10(11)). Specifically, fetal sclera showed increased expression of mir-214, let-7c, let-7e, mir-103, mir-107, and mir-98 (1.5 to 4 fold changes, p<0.01). However, no significant regionally specific differences .i.e., posterior vs. peripheral sclera, were observed for either adult or fetal samples.
  
  
  CONCLUSIONS
  For the first time, micro-RNA expression has been catalogued in human sclera. Some micro-RNAs show age-related differential regulation, higher in the sclera of rapidly growing fetal eyes, consistent with a role in ocular growth regulation. Thus micro-RNAs represent potential targets for ocular growth manipulation, related to myopia and/or other disorders such as scleral ectasia.
authors.affiliation: School of Optometry, University of California, Berkeley, California, United States of America.
authors.forename: Ravikanth
authors.initials: R
authors.lastname: Metlapally
authors.forename: Pedro
authors.initials: P
authors.lastname: Gonzalez
authors.forename: Felicia A
authors.initials: FA
authors.lastname: Hawthorne
authors.forename: Khanh-Nhat
authors.initials: KN
authors.lastname: Tran-Viet
authors.forename: Christine F
authors.initials: CF
authors.lastname: Wildsoet
authors.forename: Terri L
authors.initials: TL
authors.lastname: Young
mesh_terms: D000367:Age Factors; D005260:Female; D047109:Fetal Development; D005333:Fetus / Q000033:anatomy & histology / Q000378:metabolism*; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D006801:Humans; D008297:Male; D035683:MicroRNAs / Q000378:metabolism*; D008875:Middle Aged; D020411:Oligonucleotide Array Sequence Analysis; D012590:Sclera / Q000196:embryology / Q000254:growth & development / Q000378:metabolism*
chemical_list: D035683:MicroRNAs