Differentially expressed genes associated with human limbal epithelial phenotypes: new molecules that potentially facilitate selection of stem cell-enriched populations.
OBJECTIVE
The aim of this study was to identify differentially expressed genes in the human limbal epithelium by microarray analysis.


METHODS
Total RNA isolates of human limbal and central corneal epithelia were used after transcription for hybridization on whole human genome expression microarrays. A set of differentially expressed genes detected by both microarrays was established. In the case of eight selected molecules, microarray results were confirmed by qRT-PCR, and protein expression in the cornea was examined by confocal immunofluorescence microscopy. Colocalization with the putative stem cell marker C/EBPδ was also examined.


RESULTS
The authors established a database of 126 limbal overexpressed genes. qRT-PCR confirmed microarray results in all examined cases (SPON1, IFITM1, ITM2A, PHLDA1, CXCR4, FZD7, DCT, DKK4). Limbal localization of the protein product of SPON1, IFITM1, ITM2A, CXCR4, and DKK4 was shown with confocal immunofluorescence microscopy. SPON1, IFITM1, and ITM2A signals mostly colocalized with C/EBPδ-positive putative resting limbal stem cells.


CONCLUSIONS
By detecting several new differentially expressed genes in the human corneal limbus, this study further expands current knowledge on the molecular signature of limbal epithelial stem cells. Plasma membrane localization of IFITM1 and ITM2A suggests their potential usefulness as targets to select stem cell-enriched populations from the limbal epithelium.
Department of Ophthalmology, Medical and Health Science Center, University of Debrecen, Debrecen, Hungary. ltakacs@dote.hu
Lili
L
Takács
Eniko
E
Tóth
Gergely
G
Losonczy
Attila
A
Szanto
Tomi
T
Bähr-Ivacevic
Vladimir
V
Benes
András
A
Berta
György
G
Vereb
D015415:Biomarkers / Q000378:metabolism; D051743:CCAAT-Enhancer-Binding Protein-delta / Q000235:genetics; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism; D019573:Epithelium, Corneal / Q000166:cytology* / Q000378:metabolism*; D005136:Eye Proteins / Q000235:genetics; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000502:physiology*; D006801:Humans; D016850:Limbus Corneae / Q000166:cytology*; D018613:Microscopy, Confocal; D020411:Oligonucleotide Array Sequence Analysis; D010641:Phenotype; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013234:Stem Cells / Q000166:cytology* / Q000378:metabolism
D015415:Biomarkers; D005136:Eye Proteins; D012333:RNA, Messenger; D051743:CCAAT-Enhancer-Binding Protein-delta