Abstract
Abstract: :
Purpose: To elucidate global and differential gene expression patterns of the adult and post–natal day 10 (P10) mouse cornea and discover novel cornea genes, using the tendon and lens as comparative tissues, to further understand post–natal maturation and maintenance of the cornea. Methods: Microarray analysis (MG–U74Av2, Affymetrix) was performed on the adult cornea, P10 cornea, tendon, and lens. Expression data were analyzed by Microarray Suite v5.0 and dChip2004 software. RT–PCR, Northern blot analysis, and immunohistochemistry were used to confirm the presence of selected genes in the cornea. Results:Forty percent of the genes queried (12,488 per microarray) were expressed in at least one of the four tissue types. Functional clustering of the expressed genes revealed skewed over–representation of distinct functional groups in each tissue type; tendon (ECM), lens (crystallins), adult cornea (biosynthesis and metabolism), and P10 cornea (development). Some of these genes have known functions in the cornea (Aldh3a1, Col7a1, Muc1, Npy, Pax6), whereas a majority are currently uncharacterized (Arhgdib, Cx3cl1, Efnb2, Mal, Sfn, Tacstd2, Xlr4). A direct comparison of the adult and P10 cornea expression data identified nine genes over expressed in the adult cornea (Cyp24a1, Ca3, Npy, Psca) that may represent genes with a corneal maintenance function whose proteins undergo rapid turnover requiring a considerable up regulation of their message levels. In contrast, many more genes are over expressed in the P10 cornea indicative of collagen build–up and crosslinking (Col1a2, Col3a1, Col4a2, Col8a1, Col14a1, Lox), Tgf–ß signaling (Ctgf, Ltbp4), cell–matrix interaction (Ddr1, Sparc), ECM assembly and remodeling (Fbn, Timp2), and regulation of transcription (Cri1, Rest). We confirmed the presence of 16 genes by RT–PCR, one gene by Northern blot analysis, and two genes by immunohistochemistry. Conclusions: Analysis of the adult and P10 cornea revealed consistent and differential gene expression patterns in the maturing cornea. By comparing genes expressed in the cornea to those expressed in the lens and tendon, we identified a group of novel cornea genes whose functions have yet to be fully understood. Knowledge of gene expression patterns in the developing and mature cornea will help pave the way toward a greater understanding of the forces contributing to the maturation and maintenance of this remarkable tissue.
Keywords: cornea: basic science • gene microarray • gene/expression