Adult Ocular Tissues Research Articles

Whole genome expression profiling of normal human fetal and adult ocular tissues

To study growth and development of ocular tissues, gene expression patterns in normal human fetal versus adult eyes were compared. Human retina/retinal pigment epithelium, choroid, sclera, optic nerve* and cornea* tissues were dissected from fetal (24 week gestational age) (N = 9; *N = 6), and adult (N = 6) normal donor eyes. The Illumina® whole genome expression microarray platform was used to assess differential expression. Statistical significance for all comparisons was determined using the Benjamin and Hochberg False Discovery Rate (FDR, 5%). Significant gene expression fold changes > 1.5 were found in adult versus fetal retina/RPE (N = 1185), choroid (N = 6446), sclera (N = 1349), and cornea (N = 3872), but not optic nerve. Genes showing differential expression were assessed using Ingenuity Pathway Analysis (IPA) for enriched functions and canonical pathways. In all tissues, development, cell death/growth, cancer functions, and signaling canonical pathways were enriched. There was also a general trend of down-regulation of collagen genes in adult tissues.

Transgenic Xenopus laevis with the ef1‐α promoter as an experimental tool for amphibian retinal regeneration study

Complete retinal regeneration occurs after the removal of the whole tissue in mature Xenopus laevis, as well as in the newt. Here, we produced F1 and F2 lines of transgenic X. laevis containing an EGFP gene under a translation elongation factor 1-α (ef1-α) promoter and investigated how the gene is reactivated in retinal pigmented epithelial (RPE) cells when the neural retina (NR) is removed. The results showed that EGFP expression is reduced in the adult ocular tissues of nonmanipulated transgenic animals, and EGFP-expressing cells are occasionally found heterogeneously in the lens, NR and RPE tissues. During retinal regeneration, the EGFP gene is reactivated in the RPE and ciliary marginal cells. Transgenic animals were also used for a transplant study because of the genetic marker of the donor tissue. Transplanted RPE clearly transdifferentiated to regenerate the retina in the ocular chamber. This study is, to our knowledge, the first report of a transgenic study of amphibian retinal regeneration, and the approach is promising for future molecular analyses.

Bone Morphogenetic Proteins and Their Receptors in the Eye

The human genome encodes at least 42 different members of the transforming growth factor-beta superfamily of growth factors. Bone morphogenetic proteins (BMPs) are the largest subfamily of proteins within the transforming growth factor-beta superfamily and are involved in numerous cellular functions including development, morphogenesis, cell proliferation, apoptosis, and extracellular matrix synthesis. This article first reviews BMPs and BMP receptors, BMP signaling pathways, and mechanisms controlling BMP signaling. Second, we review BMP and BMP receptor expression during embryonic ocular development/ differentiation and in adult ocular tissues. Lastly, future research directions with respect to BMP, BMP receptors, and ocular tissues are suggested.

Isolation and Characterization of a Novel Human paired-like Homeodomain-Containing Transcription Factor Gene, VSX1, Expressed in Ocular Tissues

Homeodomain transcription factors control cell fates during the development of all animals. The paired-like subfamily of homeodomain proteins has been particularly implicated in ocular development in different species. In this paper we report the cDNA sequence, genomic structure, localization, and expression data of a novel paired-like homeobox-containing gene, VSX1, isolated from a human embryonic craniofacial cDNA library using the degenerate-PCR approach. The composed VSX1 cDNA sequence of 1433 bp was predicted to encode a protein of 365 amino acid residues. Maximal homology at the protein level was identified with the paired-like homeoproteins of the CVC-domain family: 92–97% identity was seen in the homeodomain region with 55% overall identity to zebrafish and goldfish Vsx1 and 35% overall identity to goldfish Vsx2 and murine Chx10. The gene was found to consist of five exons that are distributed over 6.2 kb of genomic sequence. VSX1 was localized to the 20p11–q11 region, which is homologous with the distal part of mouse chromosome 2. Expression of VSX1 was detected in embryonic craniofacial and adult ocular tissues. Several ocular phenotypes have been mapped to the VSX1 region in both human and mouse genomes, and its candidacy for these disorders is discussed.

Hedgehog and patched gene expression in adult ocular tissues

We analysed the expression of members of the hh gene family in adult ocular tissues of newt, frog and mouse by RT-PCR method. Shh displayed restricted expression in the neural retina that was conserved in each species analyzed. X-bhh, X-chh and mouse Ihh were detected in the iris and in the retinal pigment epithelium, while mouse Dhh was detected additionally in the neural retina and faintly in the cornea. We also found that two types of ptc genes, potential hh targets and receptors, were expressed in these tissues, suggesting the presence of active hh signalling there.

3-amino-triazole effects on the eye of young and adult rabbits in the presence and absence of hydrogen peroxide.

3-aminotriazole (3AT) is known to reduce catalase levels in ocular tissues when given intravenously or orally. Rabbits were given either 4 ml/kg of a 3M solution of 3AT intravenously or a 2% solution as drinking fluid. Intravenous 3AT administration was followed at 4 hrs by an intracameral injection of hydrogen peroxide (H2O2) to give an aqueous humor concentration of 3.2 mM in young (4-6 weeks of age) and a 3.3 mM in adult (6 months of age) rabbits. Tissues were taken for microscopy at either 6 or 24 hours after intracameral H2O2. Neither oral nor intravenous 3AT alone in adult rabbits, or intravenous 3AT in young rabbits, had any effect on either iris, ciliary process, or corneal endothelial morphology. After oral 3AT in adult rabbits, H2O2 caused highly edematous ciliary processes with dilated vessels; corneal endothelial cells were swollen. Previous studies in adult and young rabbits have shown that intracameral H2O2 alone caused few morphological changes in young, but marked changes in the adult that correlated with the 35 to 50% lower catalase levels found in iris and corneal endothelium, respectively, in adult ocular tissues. Young rabbits pre-treated with intravenous 3AT, when examined at 6 and 24 hours after intracameral H2O2, showed swollen ciliary processes, vessel dilation, alteration of the pigment epithelium and corneal endothelial damage. In non 3AT-treated young rabbits, H2O2 caused only minor morphological changes. In adult animals at 6 and 24 hours after intracameral H2O2 the ciliary processes were edematous in the absence of 3AT; after intravenous 3AT and intracameral H2O2 the changes were even more marked, with very severe swelling of ciliary processes and corneal endothelial damage. It is apparent that the decrease in catalase caused by 3AT allows H2O2 to induce damage even in young animals where it usually does not induce morphological changes. In adult animals, the effects of H2O2 are enhanced in the presence of 3AT.